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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group B. Desruisseaux, Ed. 3 Internet-Draft Oracle 4 Obsoletes: 2445 (if approved) October 11, 2006 5 Expires: April 14, 2007 7 Internet Calendaring and Scheduling Core Object Specification 8 (iCalendar) 9 draft-ietf-calsify-rfc2445bis-02 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on April 14, 2007. 36 Copyright Notice 38 Copyright (C) The Internet Society (2006). 40 Abstract 42 There is a clear need to provide and deploy interoperable calendaring 43 and scheduling services for the Internet. Current group scheduling 44 and Personal Information Management (PIM) products are being extended 45 for use across the Internet, today, in proprietary ways. This memo 46 has been defined to provide the definition of a common format for 47 openly exchanging calendaring and scheduling information across the 48 Internet. 50 This memo is formatted as a registration for a MIME media type . 51 However, the format in this memo is equally applicable for use 52 outside of a MIME message content type. 54 The proposed media type value is 'text/calendar'. This string would 55 label a media type containing calendaring and scheduling information 56 encoded as text characters formatted in a manner outlined below. 58 This MIME media type provides a standard content type for capturing 59 calendar event, to-do and journal entry information. It also can be 60 used to convey free/busy time information. The content type is 61 suitable as a MIME message entity that can be transferred over MIME 62 based email systems, using HTTP or some other Internet transport. In 63 addition, the content type is useful as an object for interactions 64 between desktop applications using the operating system clipboard, 65 drag/drop or file systems capabilities. 67 This memo is based on the earlier work of the vCalendar specification 68 for the exchange of personal calendaring and scheduling information. 69 In order to avoid confusion with this referenced work, this memo is 70 to be known as the iCalendar specification. 72 This memo defines the format for specifying iCalendar object methods. 73 An iCalendar object method is a set of usage constraints for the 74 iCalendar object. For example, these methods might define scheduling 75 messages that request an event be scheduled, reply to an event 76 request, send a cancellation notice for an event, modify or replace 77 the definition of an event, provide a counter proposal for an 78 original event request, delegate an event request to another 79 individual, request free or busy time, reply to a free or busy time 80 request, or provide similar scheduling messages for a to-do or 81 journal entry calendar component. The iCalendar Transport-indendent 82 Interoperability Protocol (iTIP) is one such scheduling protocol. 84 Editorial Note (To be removed by RFC Editor before publication) 86 This document is a product of the Calendaring and Scheduling 87 Standards Simplification (Calsify) working group of the Internet 88 Engineering Task Force. Comments on this draft are welcomed, and 89 should be addressed to the ietf-calsify@osafoundation.org [1] mailing 90 list. The issues raised on this mailing list are being tracked at 91 the following web site: 92 http://www.ofcourseimright.com/cgi-bin/roundup/calsify. 94 Table of Contents 96 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 97 2. Basic Grammar and Conventions . . . . . . . . . . . . . . . . 6 98 2.1. Formatting Conventions . . . . . . . . . . . . . . . . . 7 99 2.2. Related Memos . . . . . . . . . . . . . . . . . . . . . . 8 100 2.3. International Considerations . . . . . . . . . . . . . . 8 101 3. iCalendar Object Specification . . . . . . . . . . . . . . . 9 102 3.1. Content Lines . . . . . . . . . . . . . . . . . . . . . . 9 103 3.1.1. List and Field Separators . . . . . . . . . . . . . . 12 104 3.1.2. Multiple Values . . . . . . . . . . . . . . . . . . . 12 105 3.1.3. Binary Content . . . . . . . . . . . . . . . . . . . 12 106 3.1.4. Character Set . . . . . . . . . . . . . . . . . . . . 13 107 3.2. Property Parameters . . . . . . . . . . . . . . . . . . . 13 108 3.2.1. Alternate Text Representation . . . . . . . . . . . . 14 109 3.2.2. Common Name . . . . . . . . . . . . . . . . . . . . . 15 110 3.2.3. Calendar User Type . . . . . . . . . . . . . . . . . 16 111 3.2.4. Delegators . . . . . . . . . . . . . . . . . . . . . 17 112 3.2.5. Delegatees . . . . . . . . . . . . . . . . . . . . . 17 113 3.2.6. Directory Entry Reference . . . . . . . . . . . . . . 18 114 3.2.7. Inline Encoding . . . . . . . . . . . . . . . . . . . 18 115 3.2.8. Format Type . . . . . . . . . . . . . . . . . . . . . 19 116 3.2.9. Free/Busy Time Type . . . . . . . . . . . . . . . . . 20 117 3.2.10. Language . . . . . . . . . . . . . . . . . . . . . . 20 118 3.2.11. Group or List Membership . . . . . . . . . . . . . . 21 119 3.2.12. Participation Status . . . . . . . . . . . . . . . . 22 120 3.2.13. Recurrence Identifier Range . . . . . . . . . . . . . 24 121 3.2.14. Alarm Trigger Relationship . . . . . . . . . . . . . 24 122 3.2.15. Relationship Type . . . . . . . . . . . . . . . . . . 25 123 3.2.16. Participation Role . . . . . . . . . . . . . . . . . 26 124 3.2.17. RSVP Expectation . . . . . . . . . . . . . . . . . . 26 125 3.2.18. Sent By . . . . . . . . . . . . . . . . . . . . . . . 27 126 3.2.19. Time Zone Identifier . . . . . . . . . . . . . . . . 28 127 3.2.20. Value Data Types . . . . . . . . . . . . . . . . . . 29 128 3.3. Property Value Data Types . . . . . . . . . . . . . . . . 30 129 3.3.1. Binary . . . . . . . . . . . . . . . . . . . . . . . 30 130 3.3.2. Boolean . . . . . . . . . . . . . . . . . . . . . . . 31 131 3.3.3. Calendar User Address . . . . . . . . . . . . . . . . 31 132 3.3.4. Date . . . . . . . . . . . . . . . . . . . . . . . . 32 133 3.3.5. Date-Time . . . . . . . . . . . . . . . . . . . . . . 32 134 3.3.6. Duration . . . . . . . . . . . . . . . . . . . . . . 35 135 3.3.7. Float . . . . . . . . . . . . . . . . . . . . . . . . 35 136 3.3.8. Integer . . . . . . . . . . . . . . . . . . . . . . . 36 137 3.3.9. Period of Time . . . . . . . . . . . . . . . . . . . 36 138 3.3.10. Recurrence Rule . . . . . . . . . . . . . . . . . . . 38 139 3.3.11. Text . . . . . . . . . . . . . . . . . . . . . . . . 43 140 3.3.12. Time . . . . . . . . . . . . . . . . . . . . . . . . 45 141 3.3.13. URI . . . . . . . . . . . . . . . . . . . . . . . . . 47 142 3.3.14. UTC Offset . . . . . . . . . . . . . . . . . . . . . 48 143 3.4. iCalendar Object . . . . . . . . . . . . . . . . . . . . 48 144 3.5. Property . . . . . . . . . . . . . . . . . . . . . . . . 49 145 3.6. Calendar Components . . . . . . . . . . . . . . . . . . . 49 146 3.6.1. Event Component . . . . . . . . . . . . . . . . . . . 51 147 3.6.2. To-do Component . . . . . . . . . . . . . . . . . . . 53 148 3.6.3. Journal Component . . . . . . . . . . . . . . . . . . 55 149 3.6.4. Free/Busy Component . . . . . . . . . . . . . . . . . 57 150 3.6.5. Time Zone Component . . . . . . . . . . . . . . . . . 60 151 3.6.6. Alarm Component . . . . . . . . . . . . . . . . . . . 67 152 3.7. Calendar Properties . . . . . . . . . . . . . . . . . . . 73 153 3.7.1. Calendar Scale . . . . . . . . . . . . . . . . . . . 73 154 3.7.2. Method . . . . . . . . . . . . . . . . . . . . . . . 74 155 3.7.3. Product Identifier . . . . . . . . . . . . . . . . . 75 156 3.7.4. Version . . . . . . . . . . . . . . . . . . . . . . . 76 157 3.8. Component Properties . . . . . . . . . . . . . . . . . . 77 158 3.8.1. Descriptive Component Properties . . . . . . . . . . 77 159 3.8.1.1. Attachment . . . . . . . . . . . . . . . . . . . 77 160 3.8.1.2. Categories . . . . . . . . . . . . . . . . . . . 78 161 3.8.1.3. Classification . . . . . . . . . . . . . . . . . 79 162 3.8.1.4. Comment . . . . . . . . . . . . . . . . . . . . . 80 163 3.8.1.5. Description . . . . . . . . . . . . . . . . . . . 81 164 3.8.1.6. Geographic Position . . . . . . . . . . . . . . . 82 165 3.8.1.7. Location . . . . . . . . . . . . . . . . . . . . 84 166 3.8.1.8. Percent Complete . . . . . . . . . . . . . . . . 85 167 3.8.1.9. Priority . . . . . . . . . . . . . . . . . . . . 86 168 3.8.1.10. Resources . . . . . . . . . . . . . . . . . . . . 88 169 3.8.1.11. Status . . . . . . . . . . . . . . . . . . . . . 88 170 3.8.1.12. Summary . . . . . . . . . . . . . . . . . . . . . 90 171 3.8.2. Date and Time Component Properties . . . . . . . . . 91 172 3.8.2.1. Date/Time Completed . . . . . . . . . . . . . . . 91 173 3.8.2.2. Date/Time End . . . . . . . . . . . . . . . . . . 92 174 3.8.2.3. Date/Time Due . . . . . . . . . . . . . . . . . . 93 175 3.8.2.4. Date/Time Start . . . . . . . . . . . . . . . . . 94 176 3.8.2.5. Duration . . . . . . . . . . . . . . . . . . . . 95 177 3.8.2.6. Free/Busy Time . . . . . . . . . . . . . . . . . 96 178 3.8.2.7. Time Transparency . . . . . . . . . . . . . . . . 97 179 3.8.3. Time Zone Component Properties . . . . . . . . . . . 98 180 3.8.3.1. Time Zone Identifier . . . . . . . . . . . . . . 99 181 3.8.3.2. Time Zone Name . . . . . . . . . . . . . . . . . 100 182 3.8.3.3. Time Zone Offset From . . . . . . . . . . . . . . 101 183 3.8.3.4. Time Zone Offset To . . . . . . . . . . . . . . . 102 184 3.8.3.5. Time Zone URL . . . . . . . . . . . . . . . . . . 102 185 3.8.4. Relationship Component Properties . . . . . . . . . . 103 186 3.8.4.1. Attendee . . . . . . . . . . . . . . . . . . . . 103 187 3.8.4.2. Contact . . . . . . . . . . . . . . . . . . . . . 106 188 3.8.4.3. Organizer . . . . . . . . . . . . . . . . . . . . 107 189 3.8.4.4. Recurrence ID . . . . . . . . . . . . . . . . . . 109 190 3.8.4.5. Related To . . . . . . . . . . . . . . . . . . . 111 191 3.8.4.6. Uniform Resource Locator . . . . . . . . . . . . 113 192 3.8.4.7. Unique Identifier . . . . . . . . . . . . . . . . 113 193 3.8.5. Recurrence Component Properties . . . . . . . . . . . 115 194 3.8.5.1. Exception Date/Times . . . . . . . . . . . . . . 115 195 3.8.5.2. Exception Rule . . . . . . . . . . . . . . . . . 116 196 3.8.5.3. Recurrence Date/Times . . . . . . . . . . . . . . 118 197 3.8.5.4. Recurrence Rule . . . . . . . . . . . . . . . . . 119 198 3.8.6. Alarm Component Properties . . . . . . . . . . . . . 128 199 3.8.6.1. Action . . . . . . . . . . . . . . . . . . . . . 129 200 3.8.6.2. Repeat Count . . . . . . . . . . . . . . . . . . 129 201 3.8.6.3. Trigger . . . . . . . . . . . . . . . . . . . . . 130 202 3.8.7. Change Management Component Properties . . . . . . . 132 203 3.8.7.1. Date/Time Created . . . . . . . . . . . . . . . . 133 204 3.8.7.2. Date/Time Stamp . . . . . . . . . . . . . . . . . 133 205 3.8.7.3. Last Modified . . . . . . . . . . . . . . . . . . 134 206 3.8.7.4. Sequence Number . . . . . . . . . . . . . . . . . 135 207 3.8.8. Miscellaneous Component Properties . . . . . . . . . 137 208 3.8.8.1. Non-standard Properties . . . . . . . . . . . . . 137 209 3.8.8.2. Request Status . . . . . . . . . . . . . . . . . 138 210 4. iCalendar Object Examples . . . . . . . . . . . . . . . . . . 141 211 5. Recommended Practices . . . . . . . . . . . . . . . . . . . . 145 212 6. Registration of Content Type Elements . . . . . . . . . . . . 146 213 6.1. Registration of New and Modified iCalendar Object 214 Methods . . . . . . . . . . . . . . . . . . . . . . . . . 146 215 6.2. Registration of New Properties . . . . . . . . . . . . . 147 216 6.2.1. Define the property . . . . . . . . . . . . . . . . . 147 217 6.2.2. Post the Property definition . . . . . . . . . . . . 148 218 6.2.3. Allow a comment period . . . . . . . . . . . . . . . 148 219 6.2.4. Submit the property for approval . . . . . . . . . . 148 220 6.3. Property Change Control . . . . . . . . . . . . . . . . . 149 221 7. Internationalization Considerations . . . . . . . . . . . . . 149 222 8. Security Considerations . . . . . . . . . . . . . . . . . . . 149 223 9. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 150 224 9.1. Media Type Registration Information . . . . . . . . . . . 150 225 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 153 226 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 154 227 11.1. Normative References . . . . . . . . . . . . . . . . . . 154 228 11.2. Informative References . . . . . . . . . . . . . . . . . 155 229 Appendix A. Change Log (to be removed by RFC Editor before 230 publication) . . . . . . . . . . . . . . . . . . . . 155 231 A.1. Changes in -02 . . . . . . . . . . . . . . . . . . . . . 155 232 A.2. Changes in -01 . . . . . . . . . . . . . . . . . . . . . 156 233 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 157 234 Intellectual Property and Copyright Statements . . . . . . . . . 158 236 1. Introduction 238 The use of calendaring and scheduling has grown considerably in the 239 last decade. Enterprise and inter-enterprise business has become 240 dependent on rapid scheduling of events and actions using this 241 information technology. However, the longer term growth of 242 calendaring and scheduling, is currently limited by the lack of 243 Internet standards for the message content types that are central to 244 these knowledgeware applications. This memo is intended to progress 245 the level of interoperability possible between dissimilar calendaring 246 and scheduling applications. This memo defines a MIME content type 247 for exchanging electronic calendaring and scheduling information. 248 The Internet Calendaring and Scheduling Core Object Specification, or 249 iCalendar, allows for the capture and exchange of information 250 normally stored within a calendaring and scheduling application; such 251 as a Personal Information Manager (PIM) or a Group Scheduling 252 product. 254 The iCalendar format is suitable as an exchange format between 255 applications or systems. The format is defined in terms of a MIME 256 content type. This will enable the object to be exchanged using 257 several transports, including but not limited to SMTP, HTTP, a file 258 system, desktop interactive protocols such as the use of a memory- 259 based clipboard or drag/drop interactions, point-to-point 260 asynchronous communication, wired-network transport, or some form of 261 unwired transport such as infrared might also be used. 263 The memo also provides for the definition of iCalendar object methods 264 that will map this content type to a set of messages for supporting 265 calendaring and scheduling operations such as requesting, replying 266 to, modifying, and canceling meetings or appointments, to-dos and 267 journal entries. The iCalendar object methods can be used to define 268 other calendaring and scheduling operations such a requesting for and 269 replying with free/busy time data. Such a scheduling protocol is 270 defined in the iCalendar Transport-independent Interoperability 271 Protocol (iTIP) defined in [I-D.ietf-calsify-2446bis]. 273 The memo also includes a formal grammar for the content type based on 274 the Internet ABNF defined in [RFC4234] . This ABNF is required for 275 the implementation of parsers and to serve as the definitive 276 reference when ambiguities or questions arise in interpreting the 277 descriptive prose definition of the memo. 279 2. Basic Grammar and Conventions 281 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 282 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and 283 "OPTIONAL" in this document are to be interpreted as described in 284 [RFC2119]. 286 This memo makes use of both a descriptive prose and a more formal 287 notation for defining the calendaring and scheduling format. 289 The notation used in this memo is the ABNF notation of [RFC4234] . 290 Readers intending on implementing this format defined in this memo 291 should be familiar with this notation in order to properly interpret 292 the specifications of this memo. 294 All numeric values used in this memo are given in decimal notation. 296 All names of properties, property parameters, enumerated property 297 values and property parameter values are case-insensitive. However, 298 all other property values are case-sensitive, unless otherwise 299 stated. 301 Note: All indented editorial notes, such as this one, are intended 302 to provide the reader with additional information. The 303 information is not essential to the building of an implementation 304 conformant with this memo. The information is provided to 305 highlight a particular feature or characteristic of the memo. 307 The format for the iCalendar object is based on the syntax of the 308 [RFC2425] content type. While the iCalendar object is not a profile 309 of the [RFC2425] content type, it does reuse a number of the elements 310 from the [RFC2425] specification. 312 2.1. Formatting Conventions 314 The mechanisms defined in this memo are defined in prose. Many of 315 the terms used to describe these have common usage that is different 316 than the standards usage of this memo. In order to reference within 317 this memo elements of the calendaring and scheduling model, core 318 object (this memo) or interoperability protocol [I-D.ietf-calsify- 319 2446bis] some formatting conventions have been used. Calendaring and 320 scheduling roles are referred to in quoted-strings of text with the 321 first character of each word in upper case. For example, "Organizer" 322 refers to a role of a "Calendar User" within the scheduling protocol 323 defined by [I-D.ietf-calsify-2446bis]. Calendar components defined 324 by this memo are referred to with capitalized, quoted-strings of 325 text. All calendar components start with the letter "V". For 326 example, "VEVENT" refers to the event calendar component, "VTODO" 327 refers to the to-do calendar component and "VJOURNAL" refers to the 328 daily journal calendar component. Scheduling methods defined by iTIP 329 [I-D.ietf-calsify-2446bis] are referred to with capitalized, quoted- 330 strings of text. For example, "REQUEST" refers to the method for 331 requesting a scheduling calendar component be created or modified, 332 "REPLY" refers to the method a recipient of a request uses to update 333 their status with the "Organizer" of the calendar component. 335 The properties defined by this memo are referred to with capitalized, 336 quoted-strings of text, followed by the word "property". For 337 example, "ATTENDEE" property refers to the iCalendar property used to 338 convey the calendar address of a calendar user. Property parameters 339 defined by this memo are referred to with lowercase, quoted-strings 340 of text, followed by the word "parameter". For example, "value" 341 parameter refers to the iCalendar property parameter used to override 342 the default data type for a property value. Enumerated values 343 defined by this memo are referred to with capitalized text, either 344 alone or followed by the word "value". For example, the "MINUTELY" 345 value can be used with the "FREQ" component of the "RECUR" data type 346 to specify repeating components based on an interval of one minute or 347 more. 349 2.2. Related Memos 351 Implementers will need to be familiar with several other memos that, 352 along with this memo, form a framework for Internet calendaring and 353 scheduling standards. This memo specifies a core specification of 354 objects, data types, properties and property parameters. 356 o iTIP [I-D.ietf-calsify-2446bis] specifies an interoperability 357 protocol for scheduling between different implementations; 359 o iMIP [I-D.ietf-calsify-rfc2447bis] specifies an Internet email 360 binding for [I-D.ietf-calsify-2446bis]. 362 This memo does not attempt to repeat the specification of concepts or 363 definitions from these other memos. Where possible, references are 364 made to the memo that provides for the specification of these 365 concepts or definitions. 367 2.3. International Considerations 369 In the rest of this document, descriptions of characters are of the 370 form "character name (codepoint)", where "codepoint" is from the US- 371 ASCII character set. The "character name" is the authoritative 372 description; (codepoint) is a reference to that character in US-ASCII 373 or US-ASCII compatible sets (for example the ISO-8859-x family, 374 UTF-8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character 375 set is used, appropriate code-point from that character set MUST be 376 chosen instead. Use of non-US-ASCII-compatible character sets is NOT 377 recommended. 379 3. iCalendar Object Specification 381 The following sections define the details of a Calendaring and 382 Scheduling Core Object Specification. This information is intended 383 to be an integral part of the MIME content type registration. In 384 addition, this information can be used independent of such content 385 registration. In particular, this memo has direct applicability for 386 use as a calendaring and scheduling exchange format in file-, memory- 387 or network-based transport mechanisms. 389 3.1. Content Lines 391 The iCalendar object is organized into individual lines of text, 392 called content lines. Content lines are delimited by a line break, 393 which is a CRLF sequence (US-ASCII decimal 13, followed by US-ASCII 394 decimal 10). 396 Lines of text SHOULD NOT be longer than 75 octets, excluding the line 397 break. Long content lines SHOULD be split into a multiple line 398 representations using a line "folding" technique. That is, a long 399 line can be split between any two characters by inserting a CRLF 400 immediately followed by a single linear white space character (i.e., 401 SPACE, US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any 402 sequence of CRLF followed immediately by a single linear white space 403 character is ignored (i.e., removed) when processing the content 404 type. 406 For example the line: 408 DESCRIPTION:This is a long description that exists on a long line. 410 Can be represented as: 412 DESCRIPTION:This is a lo 413 ng description 414 that exists on a long line. 416 The process of moving from this folded multiple line representation 417 to its single line representation is called "unfolding". Unfolding 418 is accomplished by removing the CRLF character and the linear white 419 space character that immediately follows. 421 When parsing a content line, folded lines MUST first be unfolded 422 according to the unfolding procedure described above. 424 Note: It is possible for very simple implementations to generate 425 improperly folded lines in the middle of a UTF-8 multi-octet 426 sequence. For this reason, implementations need to unfold lines 427 in such a way to properly restore the original sequence. 429 The content information associated with an iCalendar object is 430 formatted using a syntax similar to that defined by [RFC2425]. That 431 is, the content information consists of CRLF-separated content lines. 433 The following notation defines the lines of content in an iCalendar 434 object: 436 contentline = name *(";" param ) ":" value CRLF 437 ; This ABNF is just a general definition for an initial parsing 438 ; of the content line into its property name, parameter list, 439 ; and value string 441 ; When parsing a content line, folded lines MUST first 442 ; be unfolded according to the unfolding procedure 443 ; described above. When generating a content line, lines 444 ; longer than 75 octets SHOULD be folded according to 445 ; the folding procedure described above. 447 name = x-name / iana-token 449 iana-token = 1*(ALPHA / DIGIT / "-") 450 ; iCalendar identifier registered with IANA 452 x-name = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-") 453 ; Reserved for experimental use. 455 vendorid = 3*(ALPHA / DIGIT) ;Vendor identification 457 param = param-name "=" param-value 458 *("," param-value) 459 ; Each property defines the specific ABNF for the parameters 460 ; allowed on the property. Refer to specific properties for 461 ; precise parameter ABNF. 463 param-name = iana-token / x-name 465 param-value = paramtext / quoted-string 467 paramtext = *SAFE-CHAR 469 value = *VALUE-CHAR 471 quoted-string = DQUOTE *QSAFE-CHAR DQUOTE 472 QSAFE-CHAR = WSP / %x21 / %x23-7E / NON-US-ASCII 473 ; Any character except CTLs and DQUOTE 475 SAFE-CHAR = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E 476 / NON-US-ASCII 477 ; Any character except CTLs, DQUOTE, ";", ":", "," 479 VALUE-CHAR = WSP / %x21-7E / NON-US-ASCII 480 ; Any textual character 482 NON-US-ASCII = %x80-F8 483 ; Use restricted by charset parameter 484 ; on outer MIME object (UTF-8 preferred) 486 CR = %x0D 487 ; carriage return 489 LF = %x0A 490 ; line feed 492 CRLF = CR LF 493 ; Internet standard newline 495 CTL = %x00-08 / %x0A-1F / %x7F 496 ; Controls 498 ALPHA = %x41-5A / %x61-7A ; A-Z / a-z 500 DIGIT = %x30-39 501 ; 0-9 503 DQUOTE = %x22 504 ; Quotation Mark 506 WSP = SPACE / HTAB 508 SPACE = %x20 510 HTAB = %x09 512 The property value component of a content line has a format that is 513 property specific. Refer to the section describing each property for 514 a definition of this format. 516 All names of properties, property parameters, enumerated property 517 values and property parameter values are case-insensitive. However, 518 all other property values are case-sensitive, unless otherwise 519 stated. 521 3.1.1. List and Field Separators 523 Some properties and parameters allow a list of values. Values in a 524 list of values MUST be separated by a COMMA character (US-ASCII 525 decimal 44). There is no significance to the order of values in a 526 list. For those parameter values (such as those that specify URI 527 values) that are specified in quoted-strings, the individual quoted- 528 strings are separated by a COMMA character (US-ASCII decimal 44). 530 Some property values are defined in terms of multiple parts. These 531 structured property values MUST have their value parts separated by a 532 SEMICOLON character (US-ASCII decimal 59). 534 Some properties allow a list of parameters. Each property parameter 535 in a list of property parameters MUST be separated by a SEMICOLON 536 character (US-ASCII decimal 59). 538 Property parameters with values containing a COLON, a SEMICOLON or a 539 COMMA character MUST be placed in quoted text. 541 For example, in the following properties a SEMICOLON is used to 542 separate property parameters from each other, and a COMMA is used to 543 separate property values in a value list. 545 ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO: 546 jsmith@example.com 548 RDATE;VALUE=DATE:19970304,19970504,19970704,19970904 550 3.1.2. Multiple Values 552 Some properties defined in the iCalendar object can have multiple 553 values. The general rule for encoding multi-valued items is to 554 simply create a new content line for each value, including the 555 property name. However, it should be noted that some properties 556 support encoding multiple values in a single property by separating 557 the values with a COMMA character (US-ASCII decimal 44). Individual 558 property definitions should be consulted for determining whether a 559 specific property allows multiple values and in which of these two 560 forms. 562 3.1.3. Binary Content 564 Binary content information in an iCalendar object SHOULD be 565 referenced using a URI within a property value. That is the binary 566 content information SHOULD be placed in an external MIME entity that 567 can be referenced by a URI from within the iCalendar object. In 568 applications where this is not feasible, binary content information 569 can be included within an iCalendar object, but only after first 570 encoding it into text using the "BASE64" encoding method defined in 571 [RFC2045]. Inline binary contact SHOULD only be used in applications 572 whose special circumstances demand that an iCalendar object be 573 expressed as a single entity. A property containing inline binary 574 content information MUST specify the "ENCODING" property parameter. 575 Binary content information placed external to the iCalendar object 576 MUST be referenced by a uniform resource identifier (URI). 578 The following example specifies an "ATTACH" property that references 579 an attachment external to the iCalendar object with a URI reference: 581 ATTACH:http://example.com/public/quarterly-report.doc 583 The following example specifies an "ATTACH" property with inline 584 binary encoded content information: 586 ATTACH;FMTTYPE=image/basic;ENCODING=BASE64;VALUE=BINARY: 587 MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1U 588 EBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIE 589 <...remainder of "BASE64" encoded binary data...> 591 3.1.4. Character Set 593 There is not a property parameter to declare the charset used in a 594 property value. The default charset for an iCalendar stream is UTF-8 595 as defined in [RFC3629] . 597 The "charset" Content-Type parameter MUST be used in MIME transports 598 to specify the charset being used . 600 3.2. Property Parameters 602 A property can have attributes associated with it. These "property 603 parameters" contain meta-information about the property or the 604 property value. Property parameters are provided to specify such 605 information as the location of an alternate text representation for a 606 property value, the language of a text property value, the data type 607 of the property value and other attributes. 609 Property parameter values that contain the COLON (US-ASCII decimal 610 58), SEMICOLON (US-ASCII decimal 59) or COMMA (US-ASCII decimal 44) 611 character separators MUST be specified as quoted-string text values. 612 Property parameter values MUST NOT contain the DQUOTE (US-ASCII 613 decimal 22) character. The DQUOTE (US-ASCII decimal 22) character is 614 used as a delimiter for parameter values that contain restricted 615 characters or URI text. For example: 617 DESCRIPTION;ALTREP="http://www.example.org":The Fall'98 Wild 618 Wizards Conference - - Las Vegas\, NV\, USA 620 Property parameter values that are not in quoted strings are case 621 insensitive. 623 The general property parameters defined by this memo are defined by 624 the following notation: 626 parameter = altrepparam ; Alternate text representation 627 / cnparam ; Common name 628 / cutypeparam ; Calendar user type 629 / delfromparam ; Delegator 630 / deltoparam ; Delegatee 631 / dirparam ; Directory entry 632 / encodingparam ; Inline encoding 633 / fmttypeparam ; Format type 634 / fbtypeparam ; Free/busy time type 635 / languageparam ; Language for text 636 / memberparam ; Group or list membership 637 / partstatparam ; Participation status 638 / rangeparam ; Recurrence identifier range 639 / trigrelparam ; Alarm trigger relationship 640 / reltypeparam ; Relationship type 641 / roleparam ; Participation role 642 / rsvpparam ; RSVP expectation 643 / sentbyparam ; Sent by 644 / tzidparam ; Reference to time zone object 645 / valuetypeparam ; Property value data type 646 / ianaparam 647 ; Some other IANA registered iCalendar parameter. 648 / xparam 649 ; A non-standard, experimental parameter. 651 ianaparam = iana-token "=" param-value *("," param-value) 653 xparam = x-name "=" param-value *("," param-value) 655 3.2.1. Alternate Text Representation 657 Parameter Name: ALTREP 659 Purpose: To specify an alternate text representation for the property 660 value. 662 Format Definition: The property parameter is defined by the following 663 notation: 665 altrepparam = "ALTREP" "=" DQUOTE uri DQUOTE 667 Description: The parameter specifies a URI that points to an 668 alternate representation for a textual property value. A property 669 specifying this parameter MUST also include a value that reflects 670 the default representation of the text value. The individual URI 671 parameter values MUST each be specified in a quoted-string. 673 Example: 675 DESCRIPTION;ALTREP="CID:part3.msg.970415T083000@example.com": 676 Project XYZ Review Meeting will include the following agenda 677 items: (a) Market Overview\, (b) Finances\, (c) Project Man 678 agement 680 The "ALTREP" property parameter value might point to a "text/html" 681 content portion. 683 Content-Type:text/html 684 Content-Id: 686 687 688 689 690 691

692 Project XYZ Review Meeting will include 693 the following agenda items: 694

    695
  1. Market Overview
    2. 696
  2. Finances
    3. 697
  3. Project Management
    4. 698
699

700 701 703 3.2.2. Common Name 705 Parameter Name: CN 706 Purpose: To specify the common name to be associated with the 707 calendar user specified by the property. 709 Format Definition: The property parameter is defined by the following 710 notation: 712 cnparam = "CN" "=" param-value 714 Description: This parameter can be specified on properties with a 715 CAL-ADDRESS value type. The parameter specifies the common name 716 to be associated with the calendar user specified by the property. 717 The parameter value is text. The parameter value can be used for 718 display text to be associated with the calendar address specified 719 by the property. 721 Example: 723 ORGANIZER;CN="John Smith":MAILTO:jsmith@example.com 725 3.2.3. Calendar User Type 727 Parameter Name: CUTYPE 729 Purpose: To specify the type of calendar user specified by the 730 property. 732 Format Definition: The property parameter is defined by the following 733 notation: 735 cutypeparam = "CUTYPE" "=" 736 ("INDIVIDUAL" ; An individual 737 / "GROUP" ; A group of individuals 738 / "RESOURCE" ; A physical resource 739 / "ROOM" ; A room resource 740 / "UNKNOWN" ; Otherwise not known 741 / x-name ; Experimental type 742 / iana-token) ; Other IANA registered 743 ; type 744 ; Default is INDIVIDUAL 746 Description: This parameter can be specified on properties with a 747 CAL-ADDRESS value type. The parameter identifies the type of 748 calendar user specified by the property. If not specified on a 749 property that allows this parameter, the default is INDIVIDUAL. 751 Example: 753 ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org 755 3.2.4. Delegators 757 Parameter Name: DELEGATED-FROM 759 Purpose: To specify the calendar users that have delegated their 760 participation to the calendar user specified by the property. 762 Format Definition: The property parameter is defined by the following 763 notation: 765 delfromparam = "DELEGATED-FROM" "=" DQUOTE cal-address 766 DQUOTE *("," DQUOTE cal-address DQUOTE) 768 Description: This parameter can be specified on properties with a 769 CAL-ADDRESS value type. This parameter can be specified on a 770 property that has a value type of calendar address. This 771 parameter specifies those calendar users that have delegated their 772 participation in a group scheduled event or to-do to the calendar 773 user specified by the property. The value MUST be a MAILTO URI as 774 defined in [RFC2368] . The individual calendar address parameter 775 values MUST each be specified in a quoted-string. 777 Example: 779 ATTENDEE;DELEGATED-FROM="MAILTO:jsmith@example.com":MAILTO: 780 jdoe@example.com 782 3.2.5. Delegatees 784 Parameter Name: DELEGATED-TO 786 Purpose: To specify the calendar users to whom the calendar user 787 specified by the property has delegated participation. 789 Format Definition: The property parameter is defined by the following 790 notation: 792 deltoparam = "DELEGATED-TO" "=" DQUOTE cal-address DQUOTE 793 *("," DQUOTE cal-address DQUOTE) 795 Description: This parameter can be specified on properties with a 796 CAL-ADDRESS value type. This parameter specifies those calendar 797 users whom have been delegated participation in a group scheduled 798 event or to-do by the calendar user specified by the property. 799 The value MUST be a MAILTO URI as defined in [RFC2368] . The 800 individual calendar address parameter values MUST each be 801 specified in a quoted-string. 803 Example: 805 ATTENDEE;DELEGATED-TO="MAILTO:jdoe@example.com","MAILTO:jqpublic 806 @example.com":MAILTO:jsmith@example.com 808 3.2.6. Directory Entry Reference 810 Parameter Name: DIR 812 Purpose: To specify reference to a directory entry associated with 813 the calendar user specified by the property. 815 Format Definition: The property parameter is defined by the following 816 notation: 818 dirparam = "DIR" "=" DQUOTE uri DQUOTE 820 Description: This parameter can be specified on properties with a 821 CAL-ADDRESS value type. The parameter specifies a reference to 822 the directory entry associated with the calendar user specified by 823 the property. The parameter value is a URI. The URI parameter 824 value MUST be specified in a quoted-string. 826 Example: 828 ORGANIZER;DIR="ldap://example.com:6666/o=ABC%20Industries, 829 c=US???(cn=Jim%20Dolittle)":MAILTO:jimdo@example.com 831 3.2.7. Inline Encoding 833 Parameter Name: ENCODING 835 Purpose: To specify an alternate inline encoding for the property 836 value. 838 Format Definition: The property parameter is defined by the following 839 notation: 841 encodingparam = "ENCODING" "=" 842 ("8BIT" 843 ; "8bit" text encoding is defined in [RFC2045] 844 / "BASE64" 845 ; "BASE64" binary encoding format is defined in [RFC2045] 846 / iana-token 847 ; Some other IANA registered iCalendar encoding type 848 / x-name) 849 ; A non-standard, experimental encoding type 851 Description: The property parameter identifies the inline encoding 852 used in a property value. The default encoding is "8BIT", 853 corresponding to a property value consisting of text. The 854 "BASE64" encoding type corresponds to a property value encoded 855 using the "BASE64" encoding defined in [RFC2045]. 857 If the value type parameter is ";VALUE=BINARY", then the inline 858 encoding parameter MUST be specified with the value 859 ";ENCODING=BASE64". 861 Example: 863 ATTACH;FMTYPE=IMAGE/JPEG;ENCODING=BASE64;VALUE=BINARY:MIICajC 864 CAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDA 865 qBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRw 866 <...remainder of "BASE64" encoded binary data...> 868 3.2.8. Format Type 870 Parameter Name: FMTTYPE 872 Purpose: To specify the content type of a referenced object. 874 Format Definition: The property parameter is defined by the following 875 notation: 877 fmttypeparam = "FMTTYPE" "=" iana-token 878 ; A IANA registered content type 879 / x-name 880 ; A non-standard content type 882 Description: This parameter can be specified on properties that are 883 used to reference an object. The parameter specifies the content 884 type of the referenced object. For example, on the "ATTACH" 885 property, a FTP type URI value does not, by itself, necessarily 886 convey the type of content associated with the resource. The 887 parameter value MUST be the TEXT for either an IANA registered 888 content type or a non-standard content type. 890 Example: 892 ATTACH;FMTTYPE=application/msword:ftp://example.com/pub/docs/ 893 agenda.doc 895 3.2.9. Free/Busy Time Type 897 Parameter Name: FBTYPE 899 Purpose: To specify the free or busy time type. 901 Format Definition: The property parameter is defined by the following 902 notation: 904 fbtypeparam = "FBTYPE" "=" ("FREE" / "BUSY" 905 / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE" 906 / x-name 907 ; Some experimental iCalendar data type. 908 / iana-token) 909 ; Some other IANA registered iCalendar data type. 911 Description: The parameter specifies the free or busy time type. The 912 value FREE indicates that the time interval is free for 913 scheduling. The value BUSY indicates that the time interval is 914 busy because one or more events have been scheduled for that 915 interval. The value BUSY-UNAVAILABLE indicates that the time 916 interval is busy and that the interval can not be scheduled. The 917 value BUSY-TENTATIVE indicates that the time interval is busy 918 because one or more events have been tentatively scheduled for 919 that interval. If not specified on a property that allows this 920 parameter, the default is BUSY. 922 Example: The following is an example of this parameter on a FREEBUSY 923 property. 925 FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z 927 3.2.10. Language 929 Parameter Name: LANGUAGE 931 Purpose: To specify the language for text values in a property or 932 property parameter. 934 Format Definition: The property parameter is defined by the following 935 notation: 937 languageparam = "LANGUAGE" "=" language 939 language = 943 Description: The parameter identifies the language of the text in the 944 property or property parameter value. The value of the "language" 945 property parameter is that defined in [RFC3066] . 947 For transport in a MIME entity, the Content-Language header field 948 can be used to set the default language for the entire body part. 949 Otherwise, no default language is assumed. 951 Example: 953 SUMMARY;LANGUAGE=us-EN:Company Holiday Party 955 LOCATION;LANGUAGE=en:Germany 957 LOCATION;LANGUAGE=no:Tyskland 959 The following example makes use of the Quoted-Printable encoding 960 in order to represent non-ASCII characters. 962 LOCATION;LANGUAGE=3Dda:K=C3=B8benhavn 964 LOCATION;LANGUAGE=en:Copenhagen 966 3.2.11. Group or List Membership 968 Parameter Name: MEMBER 970 Purpose: To specify the group or list membership of the calendar user 971 specified by the property. 973 Format Definition: The property parameter is defined by the following 974 notation: 976 memberparam = "MEMBER" "=" DQUOTE cal-address DQUOTE 977 *("," DQUOTE cal-address DQUOTE) 979 Description: This parameter can be specified on properties with a 980 CAL-ADDRESS value type. The parameter identifies the groups or 981 list membership for the calendar user specified by the property. 982 The parameter value either a single calendar address in a quoted- 983 string or a COMMA character (US-ASCII decimal 44) list of calendar 984 addresses, each in a quoted-string. The individual calendar 985 address parameter values MUST each be specified in a quoted- 986 string. 988 Example: 990 ATTENDEE;MEMBER="MAILTO:ietf-calsch@example.org":MAILTO: 991 jsmith@example.com 993 ATTENDEE;MEMBER="MAILTO:projectA@example.com","MAILTO:pr 994 ojectB@example.com":MAILTO:janedoe@example.com 996 3.2.12. Participation Status 998 Parameter Name: PARTSTAT 1000 Purpose: To specify the participation status for the calendar user 1001 specified by the property. 1003 Format Definition: The property parameter is defined by the following 1004 notation: 1006 partstatparam = "PARTSTAT" "=" 1007 ("NEEDS-ACTION" ; Event needs action 1008 / "ACCEPTED" ; Event accepted 1009 / "DECLINED" ; Event declined 1010 / "TENTATIVE" ; Event tentatively 1011 ; accepted 1012 / "DELEGATED" ; Event delegated 1013 / x-name ; Experimental status 1014 / iana-token) ; Other IANA registered 1015 ; status 1016 ; These are the participation statuses for a "VEVENT". 1017 ; Default is NEEDS-ACTION. 1019 partstatparam /= "PARTSTAT" "=" 1020 ("NEEDS-ACTION" ; To-do needs action 1021 / "ACCEPTED" ; To-do accepted 1022 / "DECLINED" ; To-do declined 1023 / "TENTATIVE" ; To-do tentatively 1024 ; accepted 1025 / "DELEGATED" ; To-do delegated 1026 / "COMPLETED" ; To-do completed. 1027 ; COMPLETED property has 1028 ; date/time completed. 1029 / "IN-PROCESS" ; To-do in process of 1030 ; being completed 1031 / x-name ; Experimental status 1032 / iana-token) ; Other IANA registered 1033 ; status 1034 ; These are the participation statuses for a "VTODO". 1035 ; Default is NEEDS-ACTION. 1037 partstatparam /= "PARTSTAT" "=" 1038 ("NEEDS-ACTION" ; Journal needs action 1039 / "ACCEPTED" ; Journal accepted 1040 / "DECLINED" ; Journal declined 1041 / x-name ; Experimental status 1042 / iana-token) ; Other IANA registered 1043 ; status 1044 ; These are the participation statuses for a "VJOURNAL". 1045 ; Default is NEEDS-ACTION. 1047 Description: This parameter can be specified on properties with a 1048 CAL-ADDRESS value type. The parameter identifies the 1049 participation status for the calendar user specified by the 1050 property value. The parameter values differ depending on whether 1051 they are associated with a group scheduled "VEVENT", "VTODO" or 1052 "VJOURNAL". The values MUST match one of the values allowed for 1053 the given calendar component. If not specified on a property that 1054 allows this parameter, the default value is NEEDS-ACTION. 1056 Example: 1058 ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@example.com 1060 3.2.13. Recurrence Identifier Range 1062 Parameter Name: RANGE 1064 Purpose: To specify the effective range of recurrence instances from 1065 the instance specified by the recurrence identifier specified by 1066 the property. 1068 Format Definition: The property parameter is defined by the following 1069 notation: 1071 rangeparam = "RANGE" "=" ("THISANDPRIOR" 1072 ; To specify all instances prior to the recurrence identifier 1073 / "THISANDFUTURE") 1074 ; To specify the instance specified by the recurrence identifier 1075 ; and all subsequent recurrence instances 1077 Description: The parameter can be specified on a property that 1078 specifies a recurrence identifier. The parameter specifies the 1079 effective range of recurrence instances that is specified by the 1080 property. The effective range is from the recurrence identified 1081 specified by the property. If this parameter is not specified an 1082 allowed property, then the default range is the single instance 1083 specified by the recurrence identifier value of the property. The 1084 parameter value can be "THISANDPRIOR" to indicate a range defined 1085 by the recurrence identified value of the property and all prior 1086 instances. The parameter value can also be "THISANDFUTURE" to 1087 indicate a range defined by the recurrence identifier and all 1088 subsequent instances. 1090 Example: 1092 RECURRENCE-ID;RANGE=THISANDPRIOR:19980401T133000Z 1094 3.2.14. Alarm Trigger Relationship 1096 Parameter Name: RELATED 1098 Purpose: To specify the relationship of the alarm trigger with 1099 respect to the start or end of the calendar component. 1101 Format Definition: The property parameter is defined by the following 1102 notation: 1104 trigrelparam = "RELATED" "=" 1105 ("START" ; Trigger off of start 1106 / "END") ; Trigger off of end 1108 Description: The parameter can be specified on properties that 1109 specify an alarm trigger with a DURATION value type. The 1110 parameter specifies whether the alarm will trigger relative to the 1111 start or end of the calendar component. The parameter value START 1112 will set the alarm to trigger off the start of the calendar 1113 component; the parameter value END will set the alarm to trigger 1114 off the end of the calendar component. If the parameter is not 1115 specified on an allowable property, then the default is START. 1117 Example: 1119 TRIGGER;RELATED=END:PT5M 1121 3.2.15. Relationship Type 1123 Parameter Name: RELTYPE 1125 Purpose: To specify the type of hierarchical relationship associated 1126 with the calendar component specified by the property. 1128 Format Definition: The property parameter is defined by the following 1129 notation: 1131 reltypeparam = "RELTYPE" "=" 1132 ("PARENT" ; Parent relationship. Default. 1133 / "CHILD" ; Child relationship 1134 / "SIBLING ; Sibling relationship 1135 / iana-token ; Some other IANA registered 1136 ; iCalendar relationship type 1137 / x-name) ; A non-standard, experimental 1138 ; relationship type 1140 Description: This parameter can be specified on a property that 1141 references another related calendar. The parameter specifies the 1142 hierarchical relationship type of the calendar component 1143 referenced by the property. The parameter value can be PARENT, to 1144 indicate that the referenced calendar component is a superior of 1145 calendar component; CHILD to indicate that the referenced calendar 1146 component is a subordinate of the calendar component; SIBLING to 1147 indicate that the referenced calendar component is a peer of the 1148 calendar component. If this parameter is not specified on an 1149 allowable property, the default relationship type is PARENT. 1151 Example: 1153 RELATED-TO;RELTYPE=SIBLING:19960401-080045-4000F192713@ 1154 example.com 1156 3.2.16. Participation Role 1158 Parameter Name: ROLE 1160 Purpose: To specify the participation role for the calendar user 1161 specified by the property. 1163 Format Definition: The property parameter is defined by the following 1164 notation: 1166 roleparam = "ROLE" "=" 1167 ("CHAIR" ; Indicates chair of the 1168 ; calendar entity 1169 / "REQ-PARTICIPANT" ; Indicates a participant whose 1170 ; participation is required 1171 / "OPT-PARTICIPANT" ; Indicates a participant whose 1172 ; participation is optional 1173 / "NON-PARTICIPANT" ; Indicates a participant who 1174 ; is copied for information 1175 ; purposes only 1176 / x-name ; Experimental role 1177 / iana-token) ; Other IANA role 1178 ; Default is REQ-PARTICIPANT 1180 Description: This parameter can be specified on properties with a 1181 CAL-ADDRESS value type. The parameter specifies the participation 1182 role for the calendar user specified by the property in the group 1183 schedule calendar component. If not specified on a property that 1184 allows this parameter, the default value is REQ-PARTICIPANT. 1186 Example: 1188 ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@example.com 1190 3.2.17. RSVP Expectation 1192 Parameter Name: RSVP 1193 Purpose: To specify whether there is an expectation of a favor of a 1194 reply from the calendar user specified by the property value. 1196 Format Definition: The property parameter is defined by the following 1197 notation: 1199 rsvpparam = "RSVP" "=" ("TRUE" / "FALSE") 1200 ; Default is FALSE 1202 Description: This parameter can be specified on properties with a 1203 CAL-ADDRESS value type. The parameter identifies the expectation 1204 of a reply from the calendar user specified by the property value. 1205 This parameter is used by the "Organizer" to request a 1206 participation status reply from an "Attendee" of a group scheduled 1207 event or to-do. If not specified on a property that allows this 1208 parameter, the default value is FALSE. 1210 Example: 1212 ATTENDEE;RSVP=TRUE:MAILTO:jsmith@example.com 1214 3.2.18. Sent By 1216 Parameter Name: SENT-BY 1218 Purpose: To specify the calendar user that is acting on behalf of the 1219 calendar user specified by the property. 1221 Format Definition: The property parameter is defined by the following 1222 notation: 1224 sentbyparam = "SENT-BY" "=" DQUOTE cal-address DQUOTE 1226 Description: This parameter can be specified on properties with a 1227 CAL-ADDRESS value type. The parameter specifies the calendar user 1228 that is acting on behalf of the calendar user specified by the 1229 property. The parameter value MUST be a MAILTO URI as defined in 1230 [RFC2368] . The individual calendar address parameter values MUST 1231 each be specified in a quoted-string. 1233 Example: 1235 ORGANIZER;SENT-BY="MAILTO:sray@example.com":MAILTO: 1236 jsmith@example.com 1238 3.2.19. Time Zone Identifier 1240 Parameter Name: TZID 1242 Purpose: To specify the identifier for the time zone definition for a 1243 time component in the property value. 1245 Format Definition: The property parameter is defined by the following 1246 notation: 1248 tzidparam = "TZID" "=" [tzidprefix] paramtext 1250 tzidprefix = "/" 1252 Description: The parameter MUST be specified on the "DTSTART", 1253 "DTEND", "DUE", "EXDATE" and "RDATE" properties when either a 1254 DATE- TIME or TIME value type is specified and when the value is 1255 not either a UTC or a "floating" time. Refer to the DATE-TIME or 1256 TIME value type definition for a description of UTC and "floating 1257 time" formats. This property parameter specifies a text value 1258 which uniquely identifies the "VTIMEZONE" calendar component to be 1259 used when evaluating the time portion of the property. The value 1260 of the TZID property parameter will be equal to the value of the 1261 TZID property for the matching time zone definition. An 1262 individual "VTIMEZONE" calendar component MUST be specified for 1263 each unique "TZID" parameter value specified in the iCalendar 1264 object. 1266 The parameter MUST be specified on properties with a DATE-TIME 1267 value if the DATE-TIME is not either a UTC or a "floating" time. 1269 The presence of the SOLIDUS character (US-ASCII decimal 47) as a 1270 prefix, indicates that this TZID represents a unique ID in a 1271 globally defined time zone registry (when such registry is 1272 defined). 1274 Note: This document does not define a naming convention for 1275 time zone identifiers. Implementers may want to use the naming 1276 conventions defined in existing time zone specifications such 1277 as the public-domain Olson database [TZDB]. The specification 1278 of globally unique time zone identifiers is not addressed by 1279 this document and is left for future study. 1281 The following are examples of this property parameter: 1283 DTSTART;TZID=US-Eastern:19980119T020000 1285 DTEND;TZID=US-Eastern:19980119T030000 1287 The TZID property parameter MUST NOT be applied to DATE-TIME or 1288 TIME properties whose time values are specified in UTC. 1290 The use of local time in a DATE-TIME or TIME value without the 1291 TZID property parameter is to be interpreted as a local time 1292 value, regardless of the existence of "VTIMEZONE" calendar 1293 components in the iCalendar object. 1295 For more information see the sections on the data types DATE-TIME 1296 and TIME. 1298 3.2.20. Value Data Types 1300 Parameter Name: VALUE 1302 Purpose: To explicitly specify the data type format for a property 1303 value. 1305 Format Definition: The property parameter is defined by the following 1306 notation: 1308 valuetypeparam = "VALUE" "=" valuetype 1310 valuetype = ("BINARY" 1311 / "BOOLEAN" 1312 / "CAL-ADDRESS" 1313 / "DATE" 1314 / "DATE-TIME" 1315 / "DURATION" 1316 / "FLOAT" 1317 / "INTEGER" 1318 / "PERIOD" 1319 / "RECUR" 1320 / "TEXT" 1321 / "TIME" 1322 / "URI" 1323 / "UTC-OFFSET" 1324 / x-name 1325 ; Some experimental iCalendar data type. 1326 / iana-token) 1327 ; Some other IANA registered iCalendar data type. 1329 Description: The parameter specifies the data type and format of the 1330 property value. The property values MUST be of a single value 1331 type. For example, a "RDATE" property cannot have a combination 1332 of DATE- TIME and TIME value types. 1334 If the property's value is the default value type, then this 1335 parameter need not be specified. However, if the property's 1336 default value type is overridden by some other allowable value 1337 type, then this parameter MUST be specified. 1339 3.3. Property Value Data Types 1341 The properties in an iCalendar object are strongly typed. The 1342 definition of each property restricts the value to be one of the 1343 value data types, or simply value types, defined in this section. 1344 The value type for a property will either be specified implicitly as 1345 the default value type or will be explicitly specified with the 1346 "VALUE" parameter. If the value type of a property is one of the 1347 alternate valid types, then it MUST be explicitly specified with the 1348 "VALUE" parameter. 1350 3.3.1. Binary 1352 Value Name: BINARY 1354 Purpose: This value type is used to identify properties that contain 1355 a character encoding of inline binary data. For example, an 1356 inline attachment of an object code might be included in an 1357 iCalendar object. 1359 Format Definition: The value type is defined by the following 1360 notation: 1362 binary = *(4b-char) [b-end] 1363 ; A "BASE64" encoded character string, as defined by [RFC2045]. 1365 b-end = (2b-char "==") / (3b-char "=") 1367 b-char = ALPHA / DIGIT / "+" / "/" 1369 Description: Property values with this value type MUST also include 1370 the inline encoding parameter sequence of ";ENCODING=BASE64". 1371 That is, all inline binary data MUST first be character encoded 1372 using the "BASE64" encoding method defined in [RFC2045]. No 1373 additional content value encoding (i.e., BACKSLASH character 1374 encoding) is defined for this value type. 1376 Example: The following is an abridged example of a "BASE64" encoded 1377 binary value data. 1379 ATTACH;VALUE=BINARY;ENCODING=BASE64:MIICajCCAdOgAwIBAgICBEUwDQY 1380 JKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlI 1381 ENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZv 1382 <...remainder of "BASE64" encoded binary data...> 1384 3.3.2. Boolean 1386 Value Name: BOOLEAN 1388 Purpose: This value type is used to identify properties that contain 1389 either a "TRUE" or "FALSE" Boolean value. 1391 Format Definition: The value type is defined by the following 1392 notation: 1394 boolean = "TRUE" / "FALSE" 1396 Description: These values are case insensitive text. No additional 1397 content value encoding (i.e., BACKSLASH character encoding) is 1398 defined for this value type. 1400 Example: The following is an example of a hypothetical property that 1401 has a BOOLEAN value type: 1403 GIBBERISH:TRUE 1405 3.3.3. Calendar User Address 1407 Value Name: CAL-ADDRESS 1409 Purpose: This value type is used to identify properties that contain 1410 a calendar user address. 1412 Format Definition: The value type is defined by the following 1413 notation: 1415 cal-address = uri 1417 Description: The value is a URI as defined by [RFC3986] or any other 1418 IANA registered form for a URI. When used to address an Internet 1419 email transport address for a calendar user, the value MUST be a 1420 MAILTO URI, as defined by [RFC2368] . No additional content value 1421 encoding (i.e., BACKSLASH character encoding) is defined for this 1422 value type. 1424 Example: 1426 ATTENDEE:MAILTO:jane_doe@example.com 1428 3.3.4. Date 1430 Value Name: DATE 1432 Purpose: This value type is used to identify values that contain a 1433 calendar date. 1435 Format Definition: The value type is defined by the following 1436 notation: 1438 date = date-value 1440 date-value = date-fullyear date-month date-mday 1441 date-fullyear = 4DIGIT 1442 date-month = 2DIGIT ;01-12 1443 date-mday = 2DIGIT ;01-28, 01-29, 01-30, 01-31 1444 ;based on month/year 1446 Description: If the property permits, multiple "date" values are 1447 specified as a COMMA character (US-ASCII decimal 44) separated 1448 list of values. The format for the value type is expressed as the 1449 [ISO.8601.1988] complete representation, basic format for a 1450 calendar date. The textual format specifies a four-digit year, 1451 two-digit month, and two-digit day of the month. There are no 1452 separator characters between the year, month and day component 1453 text. 1455 No additional content value encoding (i.e., BACKSLASH character 1456 encoding) is defined for this value type. 1458 Example: The following represents July 14, 1997: 1460 19970714 1462 3.3.5. Date-Time 1464 Value Name: DATE-TIME 1466 Purpose: This value type is used to identify values that specify a 1467 precise calendar date and time of day. 1469 Format Definition: The value type is defined by the following 1470 notation: 1472 date-time = date "T" time ;As specified in the date and time 1473 ;value definitions 1475 Description: If the property permits, multiple "date-time" values are 1476 specified as a COMMA character (US-ASCII decimal 44) separated 1477 list of values. No additional content value encoding (i.e., 1478 BACKSLASH character encoding) is defined for this value type. 1480 The "DATE-TIME" data type is used to identify values that contain 1481 a precise calendar date and time of day. The format is based on 1482 the [ISO.8601.1988] complete representation, basic format for a 1483 calendar date and time of day. The text format is a concatenation 1484 of the "date", followed by the LATIN CAPITAL LETTER T character 1485 (US-ASCII decimal 84) time designator, followed by the "time" 1486 format. 1488 The "DATE-TIME" data type expresses time values in three forms: 1490 The form of date and time with UTC offset MUST NOT be used. For 1491 example, the following is not valid for a date-time value: 1493 DTSTART:19980119T230000-0800 ;Invalid time format 1495 FORM #1: DATE WITH LOCAL TIME 1497 The date with local time form is simply a date-time value that 1498 does not contain the UTC designator nor does it reference a time 1499 zone. For example, the following represents January 18, 1998, at 1500 11 PM: 1502 DTSTART:19980118T230000 1504 Date-time values of this type are said to be "floating" and are 1505 not bound to any time zone in particular. They are used to 1506 represent the same hour, minute, and second value regardless of 1507 which time zone is currently being observed. For example, an 1508 event can be defined that indicates that an individual will be 1509 busy from 11:00 AM to 1:00 PM every day, no matter which time zone 1510 the person is in. In these cases, a local time can be specified. 1511 The recipient of an iCalendar object with a property value 1512 consisting of a local time, without any relative time zone 1513 information, SHOULD interpret the value as being fixed to whatever 1514 time zone the ATTENDEE is in at any given moment. This means that 1515 two ATTENDEEs, in different time zones, receiving the same event 1516 definition as a floating time, may be participating in the event 1517 at different actual times. Floating time SHOULD only be used 1518 where that is the reasonable behavior. 1520 In most cases, a fixed time is desired. To properly communicate a 1521 fixed time in a property value, either UTC time or local time with 1522 time zone reference MUST be specified. 1524 The use of local time in a DATE-TIME value without the TZID 1525 property parameter is to be interpreted as floating time, 1526 regardless of the existence of "VTIMEZONE" calendar components in 1527 the iCalendar object. 1529 FORM #2: DATE WITH UTC TIME 1531 The date with UTC time, or absolute time, is identified by a LATIN 1532 CAPITAL LETTER Z suffix character (US-ASCII decimal 90), the UTC 1533 designator, appended to the time value. For example, the 1534 following represents January 19, 1998, at 0700 UTC: 1536 DTSTART:19980119T070000Z 1538 The TZID property parameter MUST NOT be applied to DATE-TIME 1539 properties whose time values are specified in UTC. 1541 FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE 1543 The date and local time with reference to time zone information is 1544 identified by the use the TZID property parameter to reference the 1545 appropriate time zone definition. TZID is discussed in detail in 1546 Section 3.2.19 . For example, the following represents 2 AM in 1547 New York on Janurary 19, 1998: 1549 DTSTART;TZID=US-Eastern:19980119T020000 1551 Example: The following represents July 14, 1997, at 1:30 PM in New 1552 York City in each of the three time formats, using the "DTSTART" 1553 property. 1555 DTSTART:19970714T133000 ;Local time 1556 DTSTART:19970714T173000Z ;UTC time 1557 DTSTART;TZID=US-Eastern:19970714T133000 ;Local time and time 1558 ; zone reference 1560 A time value MUST ONLY specify 60 seconds when specifying the 1561 periodic "leap second" in the time value. For example: 1563 COMPLETED:19970630T235960Z 1565 3.3.6. Duration 1567 Value Name: DURATION 1569 Purpose: This value type is used to identify properties that contain 1570 a duration of time. 1572 Format Definition: The value type is defined by the following 1573 notation: 1575 dur-value = (["+"] / "-") "P" (dur-date / dur-time / dur-week) 1577 dur-date = dur-day [dur-time] 1578 dur-time = "T" (dur-hour / dur-minute / dur-second) 1579 dur-week = 1*DIGIT "W" 1580 dur-hour = 1*DIGIT "H" [dur-minute] 1581 dur-minute = 1*DIGIT "M" [dur-second] 1582 dur-second = 1*DIGIT "S" 1583 dur-day = 1*DIGIT "D" 1585 Description: If the property permits, multiple "duration" values are 1586 specified by a COMMA character (US-ASCII decimal 44) separated 1587 list of values. The format is expressed as the [ISO.8601.1988] 1588 basic format for the duration of time. The format can represent 1589 durations in terms of weeks, days, hours, minutes, and seconds. 1591 No additional content value encoding (i.e., BACKSLASH character 1592 encoding) are defined for this value type. 1594 Example: A duration of 15 days, 5 hours and 20 seconds would be: 1596 P15DT5H0M20S 1598 A duration of 7 weeks would be: 1600 P7W 1602 3.3.7. Float 1604 Value Name: FLOAT 1606 Purpose: This value type is used to identify properties that contain 1607 a real number value. 1609 Format Definition: The value type is defined by the following 1610 notation: 1612 float = (["+"] / "-") 1*DIGIT ["." 1*DIGIT] 1614 Description: If the property permits, multiple "float" values are 1615 specified by a COMMA character (US-ASCII decimal 44) separated 1616 list of values. 1618 No additional content value encoding (i.e., BACKSLASH character 1619 encoding) is defined for this value type. 1621 Example: 1623 1000000.0000001 1624 1.333 1625 -3.14 1627 3.3.8. Integer 1629 Value Name: INTEGER 1631 Purpose: This value type is used to identify properties that contain 1632 a signed integer value. 1634 Format Definition: The value type is defined by the following 1635 notation: 1637 integer = (["+"] / "-") 1*DIGIT 1639 Description: If the property permits, multiple "integer" values are 1640 specified by a COMMA character (US-ASCII decimal 44) separated 1641 list of values. The valid range for "integer" is -2147483648 to 1642 2147483647. If the sign is not specified, then the value is 1643 assumed to be positive. 1645 No additional content value encoding (i.e., BACKSLASH character 1646 encoding) is defined for this value type. 1648 Example: 1650 1234567890 1651 -1234567890 1652 +1234567890 1653 432109876 1655 3.3.9. Period of Time 1657 Value Name: PERIOD 1658 Purpose: This value type is used to identify values that contain a 1659 precise period of time. 1661 Format Definition: The value type is defined by the following 1662 notation: 1664 period = period-explicit / period-start 1666 period-explicit = date-time "/" date-time 1667 ; [ISO.8601.1988] complete representation basic format for a 1668 ; period of time consisting of a start and end. The start MUST 1669 ; be before the end. 1671 period-start = date-time "/" dur-value 1672 ; [ISO.8601.1988] complete representation basic format for a 1673 ; period of time consisting of a start and positive duration 1674 ; of time. 1676 Description: If the property permits, multiple "period" values are 1677 specified by a COMMA character (US-ASCII decimal 44) separated 1678 list of values. There are two forms of a period of time. First, 1679 a period of time is identified by its start and its end. This 1680 format is expressed as the [ISO.8601.1988] complete 1681 representation, basic format for "DATE-TIME" start of the period, 1682 followed by a SOLIDUS character (US-ASCII decimal 47), followed by 1683 the "DATE-TIME" of the end of the period. The start of the period 1684 MUST be before the end of the period. Second, a period of time 1685 can also be defined by a start and a positive duration of time. 1686 The format is expressed as the [ISO.8601.1988] complete 1687 representation, basic format for the "DATE-TIME" start of the 1688 period, followed by a SOLIDUS character (US-ASCII decimal 47), 1689 followed by the [ISO.8601.1988] basic format for "DURATION" of the 1690 period. 1692 Example: The period starting at 18:00:00 UTC, on January 1, 1997 and 1693 ending at 07:00:00 UTC on January 2, 1997 would be: 1695 19970101T180000Z/19970102T070000Z 1697 The period start at 18:00:00 on January 1, 1997 and lasting 5 1698 hours and 30 minutes would be: 1700 19970101T180000Z/PT5H30M 1702 No additional content value encoding (i.e., BACKSLASH character 1703 encoding) is defined for this value type. 1705 3.3.10. Recurrence Rule 1707 Value Name: RECUR 1709 Purpose: This value type is used to identify properties that contain 1710 a recurrence rule specification. 1712 Format Definition: The value type is defined by the following 1713 notation: 1715 recur = "FREQ" = freq *( 1717 ; either UNTIL or COUNT may appear in a 'recur', 1718 ; but UNTIL and COUNT MUST NOT occur in the same 1719 ; 'recur' 1721 ( ";" "UNTIL" "=" enddate ) / 1722 ( ";" "COUNT" "=" 1*DIGIT ) / 1724 ; the rest of these keywords are optional, 1725 ; but MUST NOT occur more than once 1727 ( ";" "INTERVAL" "=" 1*DIGIT ) / 1728 ( ";" "BYSECOND" "=" byseclist ) / 1729 ( ";" "BYMINUTE" "=" byminlist ) / 1730 ( ";" "BYHOUR" "=" byhrlist ) / 1731 ( ";" "BYDAY" "=" bywdaylist ) / 1732 ( ";" "BYMONTHDAY" "=" bymodaylist ) / 1733 ( ";" "BYYEARDAY" "=" byyrdaylist ) / 1734 ( ";" "BYWEEKNO" "=" bywknolist ) / 1735 ( ";" "BYMONTH" "=" bymolist ) / 1736 ( ";" "BYSETPOS" "=" bysplist ) / 1737 ( ";" "WKST" "=" weekday ) / 1738 ( ";" x-name "=" text ) 1739 ) 1741 freq = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY" 1742 / "WEEKLY" / "MONTHLY" / "YEARLY" 1744 enddate = date 1745 / date-time ;A UTC value 1747 byseclist = seconds / ( seconds *("," seconds) ) 1749 seconds = 1DIGIT / 2DIGIT ;0 to 59 1751 byminlist = minutes / ( minutes *("," minutes) ) 1752 minutes = 1DIGIT / 2DIGIT ;0 to 59 1754 byhrlist = hour / ( hour *("," hour) ) 1756 hour = 1DIGIT / 2DIGIT ;0 to 23 1758 bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) ) 1760 weekdaynum = [([plus] ordwk / minus ordwk)] weekday 1762 plus = "+" 1764 minus = "-" 1766 ordwk = 1DIGIT / 2DIGIT ;1 to 53 1768 weekday = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA" 1769 ;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, 1770 ;FRIDAY, SATURDAY and SUNDAY days of the week. 1772 bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) ) 1774 monthdaynum = ([plus] ordmoday) / (minus ordmoday) 1776 ordmoday = 1DIGIT / 2DIGIT ;1 to 31 1778 byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) ) 1780 yeardaynum = ([plus] ordyrday) / (minus ordyrday) 1782 ordyrday = 1DIGIT / 2DIGIT / 3DIGIT ;1 to 366 1784 bywknolist = weeknum / ( weeknum *("," weeknum) ) 1786 weeknum = ([plus] ordwk) / (minus ordwk) 1788 bymolist = monthnum / ( monthnum *("," monthnum) ) 1790 monthnum = 1DIGIT / 2DIGIT ;1 to 12 1792 bysplist = setposday / ( setposday *("," setposday) ) 1794 setposday = yeardaynum 1796 Description: If the property permits, multiple "recur" values are 1797 specified by a COMMA character (US-ASCII decimal 44) separated 1798 list of values. The value type is a structured value consisting 1799 of a list of one or more recurrence grammar parts. Each rule part 1800 is defined by a NAME=VALUE pair. The rule parts are separated 1801 from each other by the SEMICOLON character (US-ASCII decimal 59). 1802 The rule parts are not ordered in any particular sequence. 1803 Individual rule parts MUST only be specified once. 1805 The FREQ rule part identifies the type of recurrence rule. This 1806 rule part MUST be specified in the recurrence rule. Valid values 1807 include SECONDLY, to specify repeating events based on an interval 1808 of a second or more; MINUTELY, to specify repeating events based 1809 on an interval of a minute or more; HOURLY, to specify repeating 1810 events based on an interval of an hour or more; DAILY, to specify 1811 repeating events based on an interval of a day or more; WEEKLY, to 1812 specify repeating events based on an interval of a week or more; 1813 MONTHLY, to specify repeating events based on an interval of a 1814 month or more; and YEARLY, to specify repeating events based on an 1815 interval of a year or more. 1817 The INTERVAL rule part contains a positive integer representing 1818 how often the recurrence rule repeats. The default value is "1", 1819 meaning every second for a SECONDLY rule, or every minute for a 1820 MINUTELY rule, every hour for an HOURLY rule, every day for a 1821 DAILY rule, every week for a WEEKLY rule, every month for a 1822 MONTHLY rule and every year for a YEARLY rule. 1824 The UNTIL rule part defines a date-time value which bounds the 1825 recurrence rule in an inclusive manner. If the value specified by 1826 UNTIL is synchronized with the specified recurrence, this date or 1827 date-time becomes the last instance of the recurrence. If 1828 specified as a date-time value, then it MUST be specified in a UTC 1829 time format. If not present, and the COUNT rule part is also not 1830 present, the RRULE is considered to repeat forever. 1832 The COUNT rule part defines the number of occurrences at which to 1833 range-bound the recurrence. The "DTSTART" property value, if 1834 specified, counts as the first occurrence. 1836 The BYSECOND rule part specifies a COMMA character (US-ASCII 1837 decimal 44) separated list of seconds within a minute. Valid 1838 values are 0 to 59. The BYMINUTE rule part specifies a COMMA 1839 character (US-ASCII decimal 44) separated list of minutes within 1840 an hour. Valid values are 0 to 59. The BYHOUR rule part 1841 specifies a COMMA character (US-ASCII decimal 44) separated list 1842 of hours of the day. Valid values are 0 to 23. 1844 The BYDAY rule part specifies a COMMA character (US-ASCII decimal 1845 44) separated list of days of the week; MO indicates Monday; TU 1846 indicates Tuesday; WE indicates Wednesday; TH indicates Thursday; 1847 FR indicates Friday; SA indicates Saturday; SU indicates Sunday. 1849 Each BYDAY value can also be preceded by a positive (+n) or 1850 negative (-n) integer. If present, this indicates the nth 1851 occurrence of the specific day within the MONTHLY or YEARLY RRULE. 1852 For example, within a MONTHLY rule, +1MO (or simply 1MO) 1853 represents the first Monday within the month, whereas -1MO 1854 represents the last Monday of the month. If an integer modifier 1855 is not present, it means all days of this type within the 1856 specified frequency. For example, within a MONTHLY rule, MO 1857 represents all Mondays within the month. 1859 The BYMONTHDAY rule part specifies a COMMA character (US-ASCII 1860 decimal 44) separated list of days of the month. Valid values are 1861 1 to 31 or -31 to -1. For example, -10 represents the tenth to 1862 the last day of the month. 1864 The BYYEARDAY rule part specifies a COMMA character (US-ASCII 1865 decimal 44) separated list of days of the year. Valid values are 1866 1 to 366 or -366 to -1. For example, -1 represents the last day 1867 of the year (December 31st) and -306 represents the 306th to the 1868 last day of the year (March 1st). 1870 The BYWEEKNO rule part specifies a COMMA character (US-ASCII 1871 decimal 44) separated list of ordinals specifying weeks of the 1872 year. Valid values are 1 to 53 or -53 to -1. This corresponds to 1873 weeks according to week numbering as defined in [ISO.8601.1988]. 1874 A week is defined as a seven day period, starting on the day of 1875 the week defined to be the week start (see WKST). Week number one 1876 of the calendar year is the first week which contains at least 1877 four (4) days in that calendar year. This rule part is only valid 1878 for YEARLY rules. For example, 3 represents the third week of the 1879 year. 1881 Note: Assuming a Monday week start, week 53 can only occur when 1882 Thursday is January 1 or if it is a leap year and Wednesday is 1883 January 1. 1885 The BYMONTH rule part specifies a COMMA character (US-ASCII 1886 decimal 44) separated list of months of the year. Valid values 1887 are 1 to 12. 1889 The WKST rule part specifies the day on which the workweek starts. 1890 Valid values are MO, TU, WE, TH, FR, SA and SU. This is 1891 significant when a WEEKLY RRULE has an interval greater than 1, 1892 and a BYDAY rule part is specified. This is also significant when 1893 in a YEARLY RRULE when a BYWEEKNO rule part is specified. The 1894 default value is MO. 1896 The BYSETPOS rule part specifies a COMMA character (US-ASCII 1897 decimal 44) separated list of values which corresponds to the nth 1898 occurrence within the set of events specified by the rule. Valid 1899 values are 1 to 366 or -366 to -1. It MUST only be used in 1900 conjunction with another BYxxx rule part. For example "the last 1901 work day of the month" could be represented as: 1903 RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1 1905 Each BYSETPOS value can include a positive (+n) or negative (-n) 1906 integer. If present, this indicates the nth occurrence of the 1907 specific occurrence within the set of occurences specified by the 1908 rule. 1910 If BYxxx rule part values are found which are beyond the available 1911 scope (ie, BYMONTHDAY=30 in February), they are simply ignored. 1913 Information, not contained in the rule, necessary to determine the 1914 various recurrence instance start time and dates are derived from 1915 the Start Time (DTSTART) entry attribute. For example, 1916 "FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the 1917 month or a time. This information would be the same as what is 1918 specified for DTSTART. 1920 BYxxx rule parts modify the recurrence in some manner. BYxxx rule 1921 parts for a period of time which is the same or greater than the 1922 frequency generally reduce or limit the number of occurrences of 1923 the recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" 1924 reduces the number of recurrence instances from all days (if 1925 BYMONTH rule part is not present) to all days in January. BYxxx 1926 rule parts for a period of time less than the frequency generally 1927 increase or expand the number of occurrences of the recurrence. 1928 For example, "FREQ=YEARLY;BYMONTH=1,2" increases the number of 1929 days within the yearly recurrence set from 1 (if BYMONTH rule part 1930 is not present) to 2. 1932 If multiple BYxxx rule parts are specified, then after evaluating 1933 the specified FREQ and INTERVAL rule parts, the BYxxx rule parts 1934 are applied to the current set of evaluated occurrences in the 1935 following order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, 1936 BYHOUR, BYMINUTE, BYSECOND and BYSETPOS; then COUNT and UNTIL are 1937 evaluated. 1939 Here is an example of evaluating multiple BYxxx rule parts. 1941 DTSTART;TZID=US-Eastern:19970105T083000 1942 RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9; 1943 BYMINUTE=30 1945 First, the "INTERVAL=2" would be applied to "FREQ=YEARLY" to 1946 arrive at "every other year". Then, "BYMONTH=1" would be applied 1947 to arrive at "every January, every other year". Then, "BYDAY=SU" 1948 would be applied to arrive at "every Sunday in January, every 1949 other year". Then, "BYHOUR=8,9" would be applied to arrive at 1950 "every Sunday in January at 8 AM and 9 AM, every other year". 1951 Then, "BYMINUTE=30" would be applied to arrive at "every Sunday in 1952 January at 8:30 AM and 9:30 AM, every other year". Then, lacking 1953 information from RRULE, the second is derived from DTSTART, to end 1954 up in "every Sunday in January at 8:30:00 AM and 9:30:00 AM, every 1955 other year". Similarly, if the BYMINUTE, BYHOUR, BYDAY, 1956 BYMONTHDAY or BYMONTH rule part were missing, the appropriate 1957 minute, hour, day or month would have been retrieved from the 1958 "DTSTART" property. 1960 No additional content value encoding (i.e., BACKSLASH character 1961 encoding) is defined for this value type. 1963 Example: The following is a rule which specifies 10 occurences which 1964 occur every other day: 1966 FREQ=DAILY;COUNT=10;INTERVAL=2 1968 There are other examples specified in the "RRULE" specification. 1970 3.3.11. Text 1972 Value Name: TEXT 1974 Purpose: This value type is used to identify values that contain 1975 human readable text. 1977 Format Definition: The value type is defined by the following 1978 notation. 1980 text = *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR) 1981 ; Folded according to description above 1983 ESCAPED-CHAR = ("\\" / "\;" / "\," / "\N" / "\n") 1984 ; \\ encodes \, \N or \n encodes newline 1985 ; \; encodes ;, \, encodes , 1987 TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B / 1988 %x5D-7E / NON-US-ASCII 1989 ; Any character except CTLs not needed by the current 1990 ; character set, DQUOTE, ";", ":", "\", "," 1992 Note: Certain other character sets may require modification of 1993 the above definitions, but this is beyond the scope of this 1994 document. 1996 Description: If the property permits, multiple "text" values are 1997 specified by a COMMA character (US-ASCII decimal 44) separated 1998 list of values. 2000 The language in which the text is represented can be controlled by 2001 the "LANGUAGE" property parameter. 2003 An intentional formatted text line break MUST only be included in 2004 a "TEXT" property value by representing the line break with the 2005 character sequence of BACKSLASH (US-ASCII decimal 92), followed by 2006 a LATIN SMALL LETTER N (US-ASCII decimal 110) or a LATIN CAPITAL 2007 LETTER N (US-ASCII decimal 78), that is "\n" or "\N". 2009 The "TEXT" property values may also contain special characters 2010 that are used to signify delimiters, such as a COMMA character for 2011 lists of values or a SEMICOLON character for structured values. 2012 In order to support the inclusion of these special characters in 2013 "TEXT" property values, they MUST be escaped with a BACKSLASH 2014 character. A BACKSLASH character (US-ASCII decimal 92) in a 2015 "TEXT" property value MUST be escaped with another BACKSLASH 2016 character. A COMMA character in a "TEXT" property value MUST be 2017 escaped with a BACKSLASH character (US-ASCII decimal 92). A 2018 SEMICOLON character in a "TEXT" property value MUST be escaped 2019 with a BACKSLASH character (US-ASCII decimal 92). However, a 2020 COLON character in a "TEXT" property value SHALL NOT be escaped 2021 with a BACKSLASH character. 2023 Example: A multiple line value of: 2025 Project XYZ Final Review 2026 Conference Room - 3B 2027 Come Prepared. 2029 would be represented as: 2031 Project XYZ Final Review\nConference Room - 3B\nCome Prepared. 2033 3.3.12. Time 2035 Value Name: TIME 2037 Purpose: This value type is used to identify values that contain a 2038 time of day. 2040 Format Definition: The data type is defined by the following 2041 notation: 2043 time = time-hour time-minute time-second [time-utc] 2045 time-hour = 2DIGIT ;00-23 2046 time-minute = 2DIGIT ;00-59 2047 time-second = 2DIGIT ;00-60 2048 ;The "60" value is used to account for "leap" seconds. 2050 time-utc = "Z" 2052 Description: If the property permits, multiple "time" values are 2053 specified by a COMMA character (US-ASCII decimal 44) separated 2054 list of values. No additional content value encoding (i.e., 2055 BACKSLASH character encoding) is defined for this value type. 2057 The "TIME" data type is used to identify values that contain a 2058 time of day. The format is based on the [ISO.8601.1988] complete 2059 representation, basic format for a time of day. The text format 2060 consists of a two-digit 24-hour of the day (i.e., values 0-23), 2061 two- digit minute in the hour (i.e., values 0-59), and two-digit 2062 seconds in the minute (i.e., values 0-60). The seconds value of 2063 60 MUST only be used to account for "leap" seconds. Fractions of 2064 a second are not supported by this format. 2066 In parallel to the "DATE-TIME" definition above, the "TIME" data 2067 type expresses time values in three forms: 2069 The form of time with UTC offset MUST NOT be used. For example, 2070 the following is NOT VALID for a time value: 2072 230000-0800 ;Invalid time format 2074 FORM #1 LOCAL TIME 2076 The local time form is simply a time value that does not contain 2077 the UTC designator nor does it reference a time zone. For 2078 example, 11:00 PM: 2080 230000 2082 Time values of this type are said to be "floating" and are not 2083 bound to any time zone in particular. They are used to represent 2084 the same hour, minute, and second value regardless of which time 2085 zone is currently being observed. For example, an event can be 2086 defined that indicates that an individual will be busy from 11:00 2087 AM to 1:00 PM every day, no matter which time zone the person is 2088 in. In these cases, a local time can be specified. The recipient 2089 of an iCalendar object with a property value consisting of a local 2090 time, without any relative time zone information, SHOULD interpret 2091 the value as being fixed to whatever time zone the ATTENDEE is in 2092 at any given moment. This means that two ATTENDEEs may 2093 participate in the same event at different UTC times; floating 2094 time SHOULD only be used where that is reasonable behavior. 2096 In most cases, a fixed time is desired. To properly communicate a 2097 fixed time in a property value, either UTC time or local time with 2098 time zone reference MUST be specified. 2100 The use of local time in a TIME value without the TZID property 2101 parameter is to be interpreted as a local time value, regardless 2102 of the existence of "VTIMEZONE" calendar components in the 2103 iCalendar object. 2105 FORM #2: UTC TIME 2107 UTC time, or absolute time, is identified by a LATIN CAPITAL 2108 LETTER Z suffix character (US-ASCII decimal 90), the UTC 2109 designator, appended to the time value. For example, the 2110 following represents 07:00 AM UTC: 2112 070000Z 2114 The TZID property parameter MUST NOT be applied to TIME properties 2115 whose time values are specified in UTC. 2117 FORM #3: LOCAL TIME AND TIME ZONE REFERENCE 2119 The local time with reference to time zone information form is 2120 identified by the use the TZID property parameter to reference the 2121 appropriate time zone definition. TZID is discussed in detail in 2122 Section 3.2.19 . 2124 Example: The following represents 8:30 AM in New York in Winter, five 2125 hours behind UTC, in each of the three formats using the "X-ABC- 2126 TIMEOFDAY" non-standard property: 2128 X-ABC-TIMEOFDAY:083000 2130 X-ABC-TIMEOFDAY:133000Z 2132 X-ABC-TIMEOFDAY;TZID=US-Eastern:083000 2134 3.3.13. URI 2136 Value Name: URI 2138 Purpose: This value type is used to identify values that contain a 2139 uniform resource identifier (URI) type of reference to the 2140 property value. 2142 Format Definition: The data type is defined by the following 2143 notation: 2145 uri = 2147 Description: This data type might be used to reference binary 2148 information, for values that are large, or otherwise undesirable 2149 to include directly in the iCalendar object. 2151 The URI value formats in RFC 1738, RFC 2111 and any other IETF 2152 registered value format can be specified. 2154 Any IANA registered URI format can be used. These include, but 2155 are not limited to, those defined in RFC 1738 and RFC 2111. 2157 When a property parameter value is a URI value type, the URI MUST 2158 be specified as a quoted-string value. 2160 No additional content value encoding (i.e., BACKSLASH character 2161 encoding) is defined for this value type. 2163 Example: The following is a URI for a network file: 2165 http://example.com/my-report.txt 2167 3.3.14. UTC Offset 2169 Value Name: UTC-OFFSET 2171 Purpose: This value type is used to identify properties that contain 2172 an offset from UTC to local time. 2174 Format Definition: The data type is defined by the following 2175 notation: 2177 utc-offset = time-numzone ;As defined above in time data type 2179 time-numzone = ("+" / "-") time-hour time-minute [time- 2180 second] 2182 Description: The PLUS SIGN (US-ASCII decimal 43) character MUST be 2183 specified for positive UTC offsets (i.e., ahead of UTC). The 2184 HYPHEN-MINUS character (US-ASCII decimal 45) MUST be specified for 2185 negative UTC offsets (i.e., behind of UTC). The value of "-0000" 2186 and "-000000" are not allowed. The time-second, if present, may 2187 not be 60; if absent, it defaults to zero. 2189 No additional content value encoding (i.e., BACKSLASH character 2190 encoding) is defined for this value type. 2192 Example: The following UTC offsets are given for standard time for 2193 New York (five hours behind UTC) and Geneva (one hour ahead of 2194 UTC): 2196 -0500 2198 +0100 2200 3.4. iCalendar Object 2202 The Calendaring and Scheduling Core Object is a collection of 2203 calendaring and scheduling information. Typically, this information 2204 will consist of a single iCalendar object. However, multiple 2205 iCalendar objects can be sequentially grouped together. The first 2206 line and last line of the iCalendar object MUST contain a pair of 2207 iCalendar object delimiter strings. The syntax for an iCalendar 2208 object is as follows: 2210 icalobject = 1*("BEGIN" ":" "VCALENDAR" CRLF 2211 icalbody 2212 "END" ":" "VCALENDAR" CRLF) 2214 The following is a simple example of an iCalendar object: 2216 BEGIN:VCALENDAR 2217 VERSION:2.0 2218 PRODID:-//hacksw/handcal//NONSGML v1.0//EN 2219 BEGIN:VEVENT 2220 UID:19970610T172345Z-AF23B2@example.com 2221 DTSTAMP:19970610T172345Z 2222 DTSTART:19970714T170000Z 2223 DTEND:19970715T035959Z 2224 SUMMARY:Bastille Day Party 2225 END:VEVENT 2226 END:VCALENDAR 2228 3.5. Property 2230 A property is the definition of an individual attribute describing a 2231 calendar object or a calendar component. A property takes the form 2232 defined by the "contentline" notation defined in Section 3.1 . 2234 The following is an example of a property: 2236 DTSTART:19960415T133000Z 2238 This memo imposes no ordering of properties within an iCalendar 2239 object. 2241 Property names, parameter names and enumerated parameter values are 2242 case insensitive. For example, the property name "DUE" is the same 2243 as "due" and "Due", DTSTART;TZID=US-Eastern:19980714T120000 is the 2244 same as DtStart;TzID=US-Eastern:19980714T120000. 2246 3.6. Calendar Components 2248 The body of the iCalendar object consists of a sequence of calendar 2249 properties and one or more calendar components. The calendar 2250 properties are attributes that apply to the calendar object as a 2251 whole. The calendar components are collections of properties that 2252 express a particular calendar semantic. For example, the calendar 2253 component can specify an event, a to-do, a journal entry, time zone 2254 information, free/busy time information, or an alarm. 2256 The body of the iCalendar object is defined by the following 2257 notation: 2259 icalbody = calprops component 2261 calprops = 2*( 2263 ; 'prodid' and 'version' are both REQUIRED, 2264 ; but MUST NOT occur more than once 2266 prodid / version / 2268 ; 'calscale' and 'method' are optional, 2269 ; but MUST NOT occur more than once 2271 calscale / 2272 method / 2274 ; 'x-prop' is OPTIONAL, 2275 ; and MAY occur more than once 2277 x-prop 2278 ) 2280 component = 1*(eventc / todoc / journalc / freebusyc / 2281 timezonec / iana-comp / x-comp) 2283 iana-comp = "BEGIN" ":" iana-token CRLF 2285 1*contentline 2287 "END" ":" iana-token CRLF 2289 x-comp = "BEGIN" ":" x-name CRLF 2291 1*contentline 2293 "END" ":" x-name CRLF 2295 An iCalendar object MUST include the "PRODID" and "VERSION" calendar 2296 properties. In addition, it MUST include at least one calendar 2297 component. Special forms of iCalendar objects are possible to 2298 publish just busy time (i.e., only a "VFREEBUSY" calendar component) 2299 or time zone (i.e., only a "VTIMEZONE" calendar component) 2300 information. In addition, a complex iCalendar object is possible 2301 that is used to capture a complete snapshot of the contents of a 2302 calendar (e.g., composite of many different calendar components). 2303 More commonly, an iCalendar object will consist of just a single 2304 "VEVENT", "VTODO" or "VJOURNAL" calendar component. 2306 3.6.1. Event Component 2308 Component Name: VEVENT 2310 Purpose: Provide a grouping of component properties that describe an 2311 event. 2313 Format Definition: A "VEVENT" calendar component is defined by the 2314 following notation: 2316 eventc = "BEGIN" ":" "VEVENT" CRLF 2317 eventprop *alarmc 2318 "END" ":" "VEVENT" CRLF 2320 eventprop = 3*( 2322 ; the following are REQUIRED, 2323 ; but MUST NOT occur more than once 2325 dtstamp / dtstart / uid / 2327 ; the following are optional, 2328 ; but MUST NOT occur more than once 2330 class / created / description / geo / 2331 last-mod / location / organizer / priority / 2332 seq / status / summary / transp / 2333 url / recurid / 2335 ; either 'dtend' or 'duration' may appear in 2336 ; a 'eventprop', but 'dtend' and 'duration' 2337 ; MUST NOT occur in the same 'eventprop' 2339 dtend / duration / 2341 ; the following are optional, 2342 ; and MAY occur more than once 2344 attach / attendee / categories / comment / 2345 contact / exdate / exrule / rstatus / related / 2346 resources / rdate / rrule / x-prop 2348 ) 2350 Description: A "VEVENT" calendar component is a grouping of component 2351 properties, and possibly including "VALARM" calendar components, 2352 that represents a scheduled amount of time on a calendar. For 2353 example, it can be an activity; such as a one-hour long, 2354 department meeting from 8:00 AM to 9:00 AM, tomorrow. Generally, 2355 an event will take up time on an individual calendar. Hence, the 2356 event will appear as an opaque interval in a search for busy time. 2357 Alternately, the event can have its Time Transparency set to 2358 "TRANSPARENT" in order to prevent blocking of the event in 2359 searches for busy time. 2361 The "VEVENT" is also the calendar component used to specify an 2362 anniversary or daily reminder within a calendar. These events 2363 have a DATE value type for the "DTSTART" property instead of the 2364 default data type of DATE-TIME. If such a "VEVENT" has a "DTEND" 2365 property, it MUST be specified as a DATE value also. The 2366 anniversary type of "VEVENT" can span more than one date (i.e, 2367 "DTEND" property value is set to a calendar date after the 2368 "DTSTART" property value). 2370 The "DTSTART" property for a "VEVENT" specifies the inclusive 2371 start of the event. For recurring events, it also specifies the 2372 very first instance in the recurrence set. The "DTEND" property 2373 for a "VEVENT" calendar component specifies the non-inclusive end 2374 of the event. For cases where a "VEVENT" calendar component 2375 specifies a "DTSTART" property with a DATE data type but no 2376 "DTEND" property, the events non-inclusive end is the end of the 2377 calendar date specified by the "DTSTART" property. For cases 2378 where a "VEVENT" calendar component specifies a "DTSTART" property 2379 with a DATE-TIME data type but no "DTEND" property, the event ends 2380 on the same calendar date and time of day specified by the 2381 "DTSTART" property. 2383 The "VEVENT" calendar component cannot be nested within another 2384 calendar component. However, "VEVENT" calendar components can be 2385 related to each other or to a "VTODO" or to a "VJOURNAL" calendar 2386 component with the "RELATED-TO" property. 2388 Example: The following is an example of the "VEVENT" calendar 2389 component used to represent a meeting that will also be opaque to 2390 searches for busy time: 2392 BEGIN:VEVENT 2393 UID:19970901T130000Z-123401@example.com 2394 DTSTAMP:19970901T130000Z 2395 DTSTART:19970903T163000Z 2396 DTEND:19970903T190000Z 2397 SUMMARY:Annual Employee Review 2398 CLASS:PRIVATE 2399 CATEGORIES:BUSINESS,HUMAN RESOURCES 2400 END:VEVENT 2402 The following is an example of the "VEVENT" calendar component 2403 used to represent a reminder that will not be opaque, but rather 2404 transparent, to searches for busy time: 2406 BEGIN:VEVENT 2407 UID:19970901T130000Z-123402@example.com 2408 DTSTAMP:19970901T130000Z 2409 DTSTART:19970401T163000Z 2410 DTEND:19970402T010000Z 2411 SUMMARY:Laurel is in sensitivity awareness class. 2412 CLASS:PUBLIC 2413 CATEGORIES:BUSINESS,HUMAN RESOURCES 2414 TRANSP:TRANSPARENT 2415 END:VEVENT 2417 The following is an example of the "VEVENT" calendar component 2418 used to represent an anniversary that will occur annually. Since 2419 it takes up no time, it will not appear as opaque in a search for 2420 busy time; no matter what the value of the "TRANSP" property 2421 indicates: 2423 BEGIN:VEVENT 2424 UID:19970901T130000Z-123403@example.com 2425 DTSTAMP:19970901T130000Z 2426 DTSTART;VALUE=DATE:19971102 2427 SUMMARY:Our Blissful Anniversary 2428 CLASS:CONFIDENTIAL 2429 CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION 2430 RRULE:FREQ=YEARLY 2431 END:VEVENT 2433 3.6.2. To-do Component 2435 Component Name: VTODO 2436 Purpose: Provide a grouping of calendar properties that describe a 2437 to-do. 2439 Format Definition: A "VTODO" calendar component is defined by the 2440 following notation: 2442 todoc = "BEGIN" ":" "VTODO" CRLF 2443 todoprop *alarmc 2444 "END" ":" "VTODO" CRLF 2446 todoprop = 2*( 2448 ; the following are REQUIRED, 2449 ; but MUST NOT occur more than once 2451 dtstamp / uid / 2453 ; the following are optional, 2454 ; but MUST NOT occur more than once 2456 class / completed / created / description / 2457 dtstart / geo / last-mod / location / organizer / 2458 percent / priority / recurid / seq / status / 2459 summary / url / 2461 ; either 'due' or 'duration' may appear in 2462 ; a 'todoprop', but 'due' and 'duration' 2463 ; MUST NOT occur in the same 'todoprop' 2465 due / duration / 2467 ; the following are optional, 2468 ; and MAY occur more than once 2470 attach / attendee / categories / comment / contact / 2471 exdate / exrule / rstatus / related / resources / 2472 rdate / rrule / x-prop 2474 ) 2476 Description: A "VTODO" calendar component is a grouping of component 2477 properties and possibly "VALARM" calendar components that 2478 represent an action-item or assignment. For example, it can be 2479 used to represent an item of work assigned to an individual; such 2480 as "turn in travel expense today". 2482 The "VTODO" calendar component cannot be nested within another 2483 calendar component. However, "VTODO" calendar components can be 2484 related to each other or to a "VEVENT" or to a "VJOURNAL" calendar 2485 component with the "RELATED-TO" property. 2487 A "VTODO" calendar component without the "DTSTART" and "DUE" (or 2488 "DURATION") properties specifies a to-do that will be associated 2489 with each successive calendar date, until it is completed. 2491 Example: The following is an example of a "VTODO" calendar component: 2493 BEGIN:VTODO 2494 UID:19970901T130000Z-123404@example.com 2495 DTSTAMP:19970901T130000Z 2496 DTSTART:19970415T133000Z 2497 DUE:19970416T045959Z 2498 SUMMARY:1996 Income Tax Preparation 2499 CLASS:CONFIDENTIAL 2500 CATEGORIES:FAMILY,FINANCE 2501 PRIORITY:1 2502 STATUS:NEEDS-ACTION 2503 END:VTODO 2505 3.6.3. Journal Component 2507 Component Name: VJOURNAL 2509 Purpose: Provide a grouping of component properties that describe a 2510 journal entry. 2512 Format Definition: A "VJOURNAL" calendar component is defined by the 2513 following notation: 2515 journalc = "BEGIN" ":" "VJOURNAL" CRLF 2516 jourprop 2517 "END" ":" "VJOURNAL" CRLF 2519 jourprop = 1*( 2521 ; the following are REQUIRED, 2522 ; but MUST NOT occur more than once 2524 dtstamp / uid / 2526 ; the following are optional, 2527 ; but MUST NOT occur more than once 2529 class / created / description / dtstart / 2530 last-mod / organizer / recurid / seq / status / 2531 summary / url / 2533 ; the following are optional, 2534 ; and MAY occur more than once 2536 attach / attendee / categories / comment / 2537 contact / exdate / exrule / related / rdate / 2538 rrule / rstatus / x-prop 2539 ) 2541 Description: A "VJOURNAL" calendar component is a grouping of 2542 component properties that represent one or more descriptive text 2543 notes associated with a particular calendar date. The "DTSTART" 2544 property is used to specify the calendar date that the journal 2545 entry is associated with. Generally, it will have a DATE value 2546 data type, but it can also be used to specify a DATE-TIME value 2547 data type. Examples of a journal entry include a daily record of 2548 a legislative body or a journal entry of individual telephone 2549 contacts for the day or an ordered list of accomplishments for the 2550 day. The "VJOURNAL" calendar component can also be used to 2551 associate a document with a calendar date. 2553 The "VJOURNAL" calendar component does not take up time on a 2554 calendar. Hence, it does not play a role in free or busy time 2555 searches - - it is as though it has a time transparency value of 2556 TRANSPARENT. It is transparent to any such searches. 2558 The "VJOURNAL" calendar component cannot be nested within another 2559 calendar component. However, "VJOURNAL" calendar components can 2560 be related to each other or to a "VEVENT" or to a "VTODO" calendar 2561 component, with the "RELATED-TO" property. 2563 Example: The following is an example of the "VJOURNAL" calendar 2564 component: 2566 BEGIN:VJOURNAL 2567 UID:19970901T130000Z-123405@example.com 2568 DTSTAMP:19970901T130000Z 2569 DTSTART;VALUE=DATE:19970317 2570 SUMMARY:Staff meeting minutes 2571 DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa 2572 and Bob. Aurora project plans were reviewed. There is currentl 2573 y no budget reserves for this project. Lisa will escalate to 2574 management. Next meeting on Tuesday.\n 2575 2. Telephone Conference: ABC Corp. sales representative called 2576 to discuss new printer. Promised to get us a demo by Friday.\n 2577 3. Henry Miller (Handsoff Insurance): Car was totaled by tree. 2578 Is looking into a loaner car. 654-2323 (tel). 2579 END:VJOURNAL 2581 3.6.4. Free/Busy Component 2583 Component Name: VFREEBUSY 2585 Purpose: Provide a grouping of component properties that describe 2586 either a request for free/busy time, describe a response to a 2587 request for free/busy time or describe a published set of busy 2588 time. 2590 Format Definition: A "VFREEBUSY" calendar component is defined by the 2591 following notation: 2593 freebusyc = "BEGIN" ":" "VFREEBUSY" CRLF 2594 fbprop 2595 "END" ":" "VFREEBUSY" CRLF 2597 fbprop = *( 2599 ; the following are optional, 2600 ; but MUST NOT occur more than once 2602 contact / dtstart / dtend / duration / dtstamp / 2603 organizer / uid / url / 2605 ; the following are optional, 2606 ; and MAY occur more than once 2608 attendee / comment / freebusy / rstatus / x-prop 2609 ) 2611 Description: A "VFREEBUSY" calendar component is a grouping of 2612 component properties that represents either a request for, a reply 2613 to a request for free or busy time information or a published set 2614 of busy time information. 2616 When used to request free/busy time information, the "ATTENDEE" 2617 property specifies the calendar users whose free/busy time is 2618 being requested; the "ORGANIZER" property specifies the calendar 2619 user who is requesting the free/busy time; the "DTSTART" and 2620 "DTEND" properties specify the window of time for which the free/ 2621 busy time is being requested; the "UID" and "DTSTAMP" properties 2622 are specified to assist in proper sequencing of multiple free/busy 2623 time requests. 2625 When used to reply to a request for free/busy time, the "ATTENDEE" 2626 property specifies the calendar user responding to the free/busy 2627 time request; the "ORGANIZER" property specifies the calendar user 2628 that originally requested the free/busy time; the "FREEBUSY" 2629 property specifies the free/busy time information (if it exists); 2630 and the "UID" and "DTSTAMP" properties are specified to assist in 2631 proper sequencing of multiple free/busy time replies. 2633 When used to publish busy time, the "ORGANIZER" property specifies 2634 the calendar user associated with the published busy time; the 2635 "DTSTART" and "DTEND" properties specify an inclusive time window 2636 that surrounds the busy time information; the "FREEBUSY" property 2637 specifies the published busy time information; and the "DTSTAMP" 2638 property specifies the date/time that iCalendar object was 2639 created. 2641 The "VFREEBUSY" calendar component cannot be nested within another 2642 calendar component. Multiple "VFREEBUSY" calendar components can 2643 be specified within an iCalendar object. This permits the 2644 grouping of Free/Busy information into logical collections, such 2645 as monthly groups of busy time information. 2647 The "VFREEBUSY" calendar component is intended for use in 2648 iCalendar object methods involving requests for free time, 2649 requests for busy time, requests for both free and busy, and the 2650 associated replies. 2652 Free/Busy information is represented with the "FREEBUSY" property. 2653 This property provides a terse representation of time periods. 2654 One or more "FREEBUSY" properties can be specified in the 2655 "VFREEBUSY" calendar component. 2657 When present in a "VFREEBUSY" calendar component, the "DTSTART" 2658 and "DTEND" properties SHOULD be specified prior to any "FREEBUSY" 2659 properties. In a free time request, these properties can be used 2660 in combination with the "DURATION" property to represent a request 2661 for a duration of free time within a specified window of time. 2663 The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") 2664 are not permitted within a "VFREEBUSY" calendar component. Any 2665 recurring events are resolved into their individual busy time 2666 periods using the "FREEBUSY" property. 2668 Example: The following is an example of a "VFREEBUSY" calendar 2669 component used to request free or busy time information: 2671 BEGIN:VFREEBUSY 2672 ORGANIZER:MAILTO:jane_doe@example.com 2673 ATTENDEE:MAILTO:john_public@example.com 2674 DTSTART:19971015T050000Z 2675 DTEND:19971016T050000Z 2676 DTSTAMP:19970901T083000Z 2677 END:VFREEBUSY 2679 The following is an example of a "VFREEBUSY" calendar component 2680 used to reply to the request with busy time information: 2682 BEGIN:VFREEBUSY 2683 ORGANIZER:MAILTO:jane_doe@example.com 2684 ATTENDEE:MAILTO:john_public@example.com 2685 DTSTAMP:19970901T100000Z 2687 FREEBUSY:19971015T050000Z/PT8H30M, 2688 19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M 2689 URL:http://example.com/pub/busy/jpublic-01.ifb 2690 COMMENT:This iCalendar file contains busy time information for 2691 the next three months. 2692 END:VFREEBUSY 2694 The following is an example of a "VFREEBUSY" calendar component 2695 used to publish busy time information. 2697 BEGIN:VFREEBUSY 2698 ORGANIZER:jsmith@example.com 2699 DTSTART:19980313T141711Z 2700 DTEND:19980410T141711Z 2701 FREEBUSY:19980314T233000Z/19980315T003000Z 2702 FREEBUSY:19980316T153000Z/19980316T163000Z 2703 FREEBUSY:19980318T030000Z/19980318T040000Z 2704 URL:http://www.example.com/calendar/busytime/jsmith.ifb 2705 END:VFREEBUSY 2707 3.6.5. Time Zone Component 2709 Component Name: VTIMEZONE 2711 Purpose: Provide a grouping of component properties that defines a 2712 time zone. 2714 Format Definition: A "VTIMEZONE" calendar component is defined by the 2715 following notation: 2717 timezonec = "BEGIN" ":" "VTIMEZONE" CRLF 2719 2*( 2721 ; 'tzid' is required, but MUST NOT occur more 2722 ; than once 2724 tzid / 2726 ; 'last-mod' and 'tzurl' are optional, 2727 but MUST NOT occur more than once 2729 last-mod / tzurl / 2731 ; one of 'standardc' or 'daylightc' MUST occur 2732 ; and each MAY occur more than once. 2734 standardc / daylightc / 2736 ; the following is optional, 2737 ; and MAY occur more than once 2739 x-prop 2741 ) 2743 "END" ":" "VTIMEZONE" CRLF 2745 standardc = "BEGIN" ":" "STANDARD" CRLF 2747 tzprop 2749 "END" ":" "STANDARD" CRLF 2751 daylightc = "BEGIN" ":" "DAYLIGHT" CRLF 2752 tzprop 2754 "END" ":" "DAYLIGHT" CRLF 2756 tzprop = 3*( 2758 ; the following are each REQUIRED, 2759 ; but MUST NOT occur more than once 2761 dtstart / tzoffsetto / tzoffsetfrom / 2763 ; the following are optional, 2764 ; and MAY occur more than once 2766 comment / rdate / rrule / tzname / x-prop 2768 ) 2770 Description: A time zone is unambiguously defined by the set of time 2771 measurement rules determined by the governing body for a given 2772 geographic area. These rules describe at a minimum the base 2773 offset from UTC for the time zone, often referred to as the 2774 Standard Time offset. Many locations adjust their Standard Time 2775 forward or backward by one hour, in order to accommodate seasonal 2776 changes in number of daylight hours, often referred to as Daylight 2777 Saving Time. Some locations adjust their time by a fraction of an 2778 hour. Standard Time is also known as Winter Time. Daylight 2779 Saving Time is also known as Advanced Time, Summer Time, or Legal 2780 Time in certain countries. The following table shows the changes 2781 in time zone rules in effect for New York City starting from 1967. 2782 Each line represents a description or rule for a particular 2783 observance. 2785 Effective Observance Rule 2787 +-----------+-------------------------+--------+--------------+ 2788 | Date | (Date/Time) | Offset | Abbreviation | 2789 +-----------+-------------------------+--------+--------------+ 2790 | 1967-* | last Sun in Oct, 02:00 | -0500 | EST | 2791 | 1967-1973 | last Sun in Apr, 02:00 | -0400 | EDT | 2792 | 1974-1974 | Jan 6, 02:00 | -0400 | EDT | 2793 | 1975-1975 | Feb 23, 02:00 | -0400 | EDT | 2794 | 1976-1986 | last Sun in Apr, 02:00 | -0400 | EDT | 2795 | 1987-* | first Sun in Apr, 02:00 | -0400 | EDT | 2796 +-----------+-------------------------+--------+--------------+ 2797 Note: The specification of a global time zone registry is not 2798 addressed by this document and is left for future study. 2799 However, implementers may find the Olson time zone database 2800 [TZDB] a useful reference. It is an informal, public-domain 2801 collection of time zone information, which is currently being 2802 maintained by volunteer Internet participants, and is used in 2803 several operating systems. This database contains current and 2804 historical time zone information for a wide variety of 2805 locations around the globe; it provides a time zone identifier 2806 for every unique time zone rule set in actual use since 1970, 2807 with historical data going back to the introduction of standard 2808 time. 2810 Interoperability between two calendaring and scheduling 2811 applications, especially for recurring events, to-dos or journal 2812 entries, is dependent on the ability to capture and convey date 2813 and time information in an unambiguous format. The specification 2814 of current time zone information is integral to this behavior. 2816 If present, the "VTIMEZONE" calendar component defines the set of 2817 Standard Time and Daylight Saving Time observances (or rules) for 2818 a particular time zone for a given interval of time. The 2819 "VTIMEZONE" calendar component cannot be nested within other 2820 calendar components. Multiple "VTIMEZONE" calendar components can 2821 exist in an iCalendar object. In this situation, each "VTIMEZONE" 2822 MUST represent a unique time zone definition. This is necessary 2823 for some classes of events, such as airline flights, that start in 2824 one time zone and end in another. 2826 The "VTIMEZONE" calendar component MUST be present if the 2827 iCalendar object contains an RRULE that generates dates on both 2828 sides of a time zone shift (e.g., both in Standard Time and 2829 Daylight Saving Time) unless the iCalendar object intends to 2830 convey a floating time ( see Section 3.3.12 for proper 2831 interpretation of floating time). It can be present if the 2832 iCalendar object does not contain such a RRULE. In addition, if a 2833 RRULE is present, there MUST be valid time zone information for 2834 all recurrence instances. 2836 The "VTIMEZONE" calendar component MUST include the "TZID" 2837 property and at least one definition of a standard or daylight 2838 component. The standard or daylight component MUST include the 2839 "DTSTART", "TZOFFSETFROM" and "TZOFFSETTO" properties. 2841 An individual "VTIMEZONE" calendar component MUST be specified for 2842 each unique "TZID" parameter value specified in the iCalendar 2843 object. 2845 Each "VTIMEZONE" calendar component consists of a collection of 2846 one or more sub-components that describe the rule for a particular 2847 observance (either a Standard Time or a Daylight Saving Time 2848 observance). The "STANDARD" sub-component consists of a 2849 collection of properties that describe Standard Time. The 2850 "DAYLIGHT" sub-component consists of a collection of properties 2851 that describe Daylight Saving Time. In general this collection of 2852 properties consists of: 2854 * the first onset date-time for the observance 2856 * the last onset date-time for the observance, if a last onset is 2857 known. 2859 * the offset to be applied for the observance 2861 * a rule that describes the day and time when the observance 2862 takes effect 2864 * an optional name for the observance 2866 For a given time zone, there may be multiple unique definitions of 2867 the observances over a period of time. Each observance is 2868 described using either a "STANDARD" or "DAYLIGHT" sub-component. 2869 The collection of these sub-components is used to describe the 2870 time zone for a given period of time. The offset to apply at any 2871 given time is found by locating the observance that has the last 2872 onset date and time before the time in question, and using the 2873 offset value from that observance. 2875 The top-level properties in a "VTIMEZONE" calendar component are: 2877 The mandatory "TZID" property is a text value that uniquely 2878 identifies the VTIMEZONE; and each MAY occur more than once. 2879 calendar component within the scope of an iCalendar object. 2881 The optional "LAST-MODIFIED" property is a UTC value that 2882 specifies the date and time that this time zone definition was 2883 last updated. 2885 The optional "TZURL" property is a url value that points to a 2886 published VTIMEZONE definition. TZURL SHOULD refer to a resource 2887 that is accessible by anyone who might need to interpret the 2888 object. This SHOULD NOT normally be a "file" URL or other URL 2889 that is not widely-accessible. 2891 The collection of properties that are used to define the STANDARD 2892 and DAYLIGHT sub-components include: 2894 The mandatory "DTSTART" property gives the effective onset date 2895 and local time for the time zone sub-component definition. 2896 "DTSTART" in this usage MUST be specified as a local DATE-TIME 2897 value. 2899 The mandatory "TZOFFSETFROM" property gives the UTC offset which 2900 is in use when the onset of this time zone observance begins. 2901 "TZOFFSETFROM" is combined with "DTSTART" to define the effective 2902 onset for the time zone sub-component definition. For example, 2903 the following represents the time at which the observance of 2904 Standard Time took effect in Fall 1967 for New York City: 2906 DTSTART:19671029T020000 2908 TZOFFSETFROM:-0400 2910 The mandatory "TZOFFSETTO " property gives the UTC offset for the 2911 time zone sub-component (Standard Time or Daylight Saving Time) 2912 when this observance is in use. 2914 The optional "TZNAME" property is the customary name for the time 2915 zone. It may be specified multiple times, to allow for specifying 2916 multiple language variants of the time zone names. This could be 2917 used for displaying dates. 2919 If specified, the onset for the observance defined by the time 2920 zone sub-component is defined by either the "RRULE" or "RDATE" 2921 property. If neither is specified, only one sub-component can be 2922 specified in the "VTIMEZONE" calendar component and it is assumed 2923 that the single observance specified is always in effect. 2925 The "RRULE" property defines the recurrence rule for the onset of 2926 the observance defined by this time zone sub-component. Some 2927 specific requirements for the usage of RRULE for this purpose 2928 include: 2930 * If observance is known to have an effective end date, the 2931 "UNTIL" recurrence rule parameter MUST be used to specify the 2932 last valid onset of this observance (i.e., the UNTIL date-time 2933 will be equal to the last instance generated by the recurrence 2934 pattern). It MUST be specified in UTC time. 2936 * The "DTSTART" and the "TZOFFSETTO" properties MUST be used when 2937 generating the onset date-time values (instances) from the 2938 RRULE. 2940 Alternatively, the "RDATE" property can be used to define the 2941 onset of the observance by giving the individual onset date and 2942 times. "RDATE" in this usage MUST be specified as a local DATE- 2943 TIME value in UTC time. 2945 The optional "COMMENT" property is also allowed for descriptive 2946 explanatory text. 2948 Example: The following are examples of the "VTIMEZONE" calendar 2949 component: 2951 This is an example showing time zone information for the Eastern 2952 United States using "RDATE" property. Note that this is only 2953 suitable for a recurring event that starts on or later than April 2954 6, 1997 at 03:00:00 EDT (i.e., the earliest effective transition 2955 date and time) and ends no later than April 7, 1998 02:00:00 EST 2956 (i.e., latest valid date and time for EST in this scenario). For 2957 example, this can be used for a recurring event that occurs every 2958 Friday, 8:00AM-9:00 AM, starting June 1, 1997, ending December 31, 2959 1997. 2961 BEGIN:VTIMEZONE 2962 TZID:US-Eastern 2963 LAST-MODIFIED:19870101T000000Z 2964 BEGIN:STANDARD 2965 DTSTART:19971026T020000 2966 RDATE:19971026T020000 2967 TZOFFSETFROM:-0400 2968 TZOFFSETTO:-0500 2969 TZNAME:EST 2970 END:STANDARD 2971 BEGIN:DAYLIGHT 2972 DTSTART:19970406T020000 2973 RDATE:19970406T020000 2974 TZOFFSETFROM:-0500 2975 TZOFFSETTO:-0400 2976 TZNAME:EDT 2977 END:DAYLIGHT 2978 END:VTIMEZONE 2980 This is a simple example showing the current time zone rules for 2981 the Eastern United States using a RRULE recurrence pattern. Note 2982 that there is no effective end date to either of the Standard Time 2983 or Daylight Time rules. This information would be valid for a 2984 recurring event starting today and continuing indefinitely. 2986 BEGIN:VTIMEZONE 2987 TZID:US-Eastern 2988 LAST-MODIFIED:19870101T000000Z 2989 TZURL:http://zones.example.com/tz/US-Eastern.ics 2990 BEGIN:STANDARD 2991 DTSTART:19671029T020000 2992 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 2993 TZOFFSETFROM:-0400 2994 TZOFFSETTO:-0500 2995 TZNAME:EST 2996 END:STANDARD 2997 BEGIN:DAYLIGHT 2998 DTSTART:19870405T020000 2999 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4 3000 TZOFFSETFROM:-0500 3001 TZOFFSETTO:-0400 3002 TZNAME:EDT 3003 END:DAYLIGHT 3004 END:VTIMEZONE 3006 This is an example showing a fictitious set of rules for the 3007 Eastern United States, where the Daylight Time rule has an 3008 effective end date (i.e., after that date, Daylight Time is no 3009 longer observed). 3011 BEGIN:VTIMEZONE 3012 TZID:US--Fictitious-Eastern 3013 LAST-MODIFIED:19870101T000000Z 3014 BEGIN:STANDARD 3015 DTSTART:19671029T020000 3016 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 3017 TZOFFSETFROM:-0400 3018 TZOFFSETTO:-0500 3019 TZNAME:EST 3020 END:STANDARD 3021 BEGIN:DAYLIGHT 3022 DTSTART:19870405T020000 3023 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z 3024 TZOFFSETFROM:-0500 3025 TZOFFSETTO:-0400 3026 TZNAME:EDT 3027 END:DAYLIGHT 3028 END:VTIMEZONE 3030 This is an example showing a fictitious set of rules for the 3031 Eastern United States, where the first Daylight Time rule has an 3032 effective end date. There is a second Daylight Time rule that 3033 picks up where the other left off. 3035 BEGIN:VTIMEZONE 3036 TZID:US--Fictitious-Eastern 3037 LAST-MODIFIED:19870101T000000Z 3038 BEGIN:STANDARD 3039 DTSTART:19671029T020000 3040 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 3041 TZOFFSETFROM:-0400 3042 TZOFFSETTO:-0500 3043 TZNAME:EST 3044 END:STANDARD 3045 BEGIN:DAYLIGHT 3046 DTSTART:19870405T020000 3047 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z 3048 TZOFFSETFROM:-0500 3049 TZOFFSETTO:-0400 3050 TZNAME:EDT 3051 END:DAYLIGHT 3052 BEGIN:DAYLIGHT 3053 DTSTART:19990424T020000 3054 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4 3055 TZOFFSETFROM:-0500 3056 TZOFFSETTO:-0400 3057 TZNAME:EDT 3058 END:DAYLIGHT 3059 END:VTIMEZONE 3061 3.6.6. Alarm Component 3063 Component Name: VALARM 3065 Purpose: Provide a grouping of component properties that define an 3066 alarm. 3068 Format Definition: A "VALARM" calendar component is defined by the 3069 following notation: 3071 alarmc = "BEGIN" ":" "VALARM" CRLF 3072 (audioprop / dispprop / emailprop / procprop) 3073 "END" ":" "VALARM" CRLF 3075 audioprop = 2*( 3076 ; 'action' and 'trigger' are both REQUIRED, 3077 ; but MUST NOT occur more than once 3079 action / trigger / 3081 ; 'duration' and 'repeat' are both optional, 3082 ; and MUST NOT occur more than once each, 3083 ; but if one occurs, so MUST the other 3085 duration / repeat / 3087 ; the following is optional, 3088 ; but MUST NOT occur more than once 3090 attach / 3092 ; the following is optional, 3093 ; and MAY occur more than once 3095 x-prop 3097 ) 3099 dispprop = 3*( 3101 ; the following are all REQUIRED, 3102 ; but MUST NOT occur more than once 3104 action / description / trigger / 3106 ; 'duration' and 'repeat' are both optional, 3107 ; and MUST NOT occur more than once each, 3108 ; but if one occurs, so MUST the other 3110 duration / repeat / 3112 ; the following is optional, 3113 ; and MAY occur more than once 3115 x-prop 3117 ) 3119 emailprop = 5*( 3121 ; the following are all REQUIRED, 3122 ; but MUST NOT occur more than once 3123 action / description / trigger / summary / 3125 ; the following is REQUIRED, 3126 ; and MAY occur more than once 3128 attendee / 3130 ; 'duration' and 'repeat' are both optional, 3131 ; and MUST NOT occur more than once each, 3132 ; but if one occurs, so MUST the other 3134 duration / repeat / 3136 ; the following are optional, 3137 ; and MAY occur more than once 3139 attach / x-prop 3141 ) 3143 procprop = 3*( 3145 ; the following are all REQUIRED, 3146 ; but MUST NOT occur more than once 3148 action / attach / trigger / 3150 ; 'duration' and 'repeat' are both optional, 3151 ; and MUST NOT occur more than once each, 3152 ; but if one occurs, so MUST the other 3154 duration / repeat / 3156 ; 'description' is optional, 3157 ; and MUST NOT occur more than once 3159 description / 3161 ; the following is optional, 3162 ; and MAY occur more than once 3164 x-prop 3166 ) 3168 Description: A "VALARM" calendar component is a grouping of component 3169 properties that is a reminder or alarm for an event or a to-do. 3170 For example, it may be used to define a reminder for a pending 3171 event or an overdue to-do. 3173 The "VALARM" calendar component MUST include the "ACTION" and 3174 "TRIGGER" properties. The "ACTION" property further constrains 3175 the "VALARM" calendar component in the following ways: 3177 When the action is "AUDIO", the alarm can also include one and 3178 only one "ATTACH" property, which MUST point to a sound resource, 3179 which is rendered when the alarm is triggered. 3181 When the action is "DISPLAY", the alarm MUST also include a 3182 "DESCRIPTION" property, which contains the text to be displayed 3183 when the alarm is triggered. 3185 When the action is "EMAIL", the alarm MUST include a "DESCRIPTION" 3186 property, which contains the text to be used as the message body, 3187 a "SUMMARY" property, which contains the text to be used as the 3188 message subject, and one or more "ATTENDEE" properties, which 3189 contain the email address of attendees to receive the message. It 3190 can also include one or more "ATTACH" properties, which are 3191 intended to be sent as message attachments. When the alarm is 3192 triggered, the email message is sent. 3194 When the action is "PROCEDURE", the alarm MUST include one and 3195 only one "ATTACH" property, which MUST point to a procedure 3196 resource, which is invoked when the alarm is triggered. 3198 The "VALARM" calendar component MUST only appear within either a 3199 "VEVENT" or "VTODO" calendar component. "VALARM" calendar 3200 components cannot be nested. Multiple mutually independent 3201 "VALARM" calendar components can be specified for a single 3202 "VEVENT" or "VTODO" calendar component. 3204 The "TRIGGER" property specifies when the alarm will be triggered. 3205 The "TRIGGER" property specifies a duration prior to the start of 3206 an event or a to-do. The "TRIGGER" edge may be explicitly set to 3207 be relative to the "START" or "END" of the event or to-do with the 3208 "RELATED" parameter of the "TRIGGER" property. The "TRIGGER" 3209 property value type can alternatively be set to an absolute 3210 calendar date and time of day value. 3212 In an alarm set to trigger on the "START" of an event or to-do, 3213 the "DTSTART" property MUST be present in the associated event or 3214 to-do. In an alarm in a "VEVENT" calendar component set to 3215 trigger on the "END" of the event, either the "DTEND" property 3216 MUST be present, or the "DTSTART" and "DURATION" properties MUST 3217 both be present. In an alarm in a "VTODO" calendar component set 3218 to trigger on the "END" of the to-do, either the "DUE" property 3219 MUST be present, or the "DTSTART" and "DURATION" properties MUST 3220 both be present. 3222 The alarm can be defined such that it triggers repeatedly. A 3223 definition of an alarm with a repeating trigger MUST include both 3224 the "DURATION" and "REPEAT" properties. The "DURATION" property 3225 specifies the delay period, after which the alarm will repeat. 3226 The "REPEAT" property specifies the number of additional 3227 repetitions that the alarm will be triggered. This repetition 3228 count is in addition to the initial triggering of the alarm. Both 3229 of these properties MUST be present in order to specify a 3230 repeating alarm. If one of these two properties is absent, then 3231 the alarm will not repeat beyond the initial trigger. 3233 The "ACTION" property is used within the "VALARM" calendar 3234 component to specify the type of action invoked when the alarm is 3235 triggered. The "VALARM" properties provide enough information for 3236 a specific action to be invoked. It is typically the 3237 responsibility of a "Calendar User Agent" (CUA) to deliver the 3238 alarm in the specified fashion. An "ACTION" property value of 3239 AUDIO specifies an alarm that causes a sound to be played to alert 3240 the user; DISPLAY specifies an alarm that causes a text message to 3241 be displayed to the user; EMAIL specifies an alarm that causes an 3242 electronic email message to be delivered to one or more email 3243 addresses; and PROCEDURE specifies an alarm that causes a 3244 procedure to be executed. The "ACTION" property MUST specify one 3245 and only one of these values. 3247 In an AUDIO alarm, if the optional "ATTACH" property is included, 3248 it MUST specify an audio sound resource. The intention is that 3249 the sound will be played as the alarm effect. If an "ATTACH" 3250 property is specified that does not refer to a sound resource, or 3251 if the specified sound resource cannot be rendered (because its 3252 format is unsupported, or because it cannot be retrieved), then 3253 the CUA or other entity responsible for playing the sound may 3254 choose a fallback action, such as playing a built-in default 3255 sound, or playing no sound at all. 3257 In a DISPLAY alarm, the intended alarm effect is for the text 3258 value of the "DESCRIPTION" property to be displayed to the user. 3260 In an EMAIL alarm, the intended alarm effect is for an email 3261 message to be composed and delivered to all the addresses 3262 specified by the "ATTENDEE" properties in the "VALARM" calendar 3263 component. The "DESCRIPTION" property of the "VALARM" calendar 3264 component MUST be used as the body text of the message, and the 3265 "SUMMARY" property MUST be used as the subject text. Any "ATTACH" 3266 properties in the "VALARM" calendar component SHOULD be sent as 3267 attachments to the message. 3269 In a PROCEDURE alarm, the "ATTACH" property in the "VALARM" 3270 calendar component MUST specify a procedure or program that is 3271 intended to be invoked as the alarm effect. If the procedure or 3272 program is in a format that cannot be rendered, then no procedure 3273 alarm will be invoked. If the "DESCRIPTION" property is present, 3274 its value specifies the argument string to be passed to the 3275 procedure or program. "Calendar User Agents" that receive an 3276 iCalendar object with this category of alarm, can disable or allow 3277 the "Calendar User" to disable, or otherwise ignore this type of 3278 alarm. While a very useful alarm capability, the PROCEDURE type 3279 of alarm SHOULD be treated by the "Calendar User Agent" as a 3280 potential security risk. 3282 Example: The following example is for a "VALARM" calendar component 3283 that specifies an audio alarm that will sound at a precise time 3284 and repeat 4 more times at 15 minute intervals: 3286 BEGIN:VALARM 3287 TRIGGER;VALUE=DATE-TIME:19970317T133000Z 3288 REPEAT:4 3289 DURATION:PT15M 3290 ACTION:AUDIO 3291 ATTACH;FMTTYPE=audio/basic:ftp://example.com/pub/ 3292 sounds/bell-01.aud 3293 END:VALARM 3295 The following example is for a "VALARM" calendar component that 3296 specifies a display alarm that will trigger 30 minutes before the 3297 scheduled start of the event or the due date/time of the to-do it 3298 is associated with and will repeat 2 more times at 15 minute 3299 intervals: 3301 BEGIN:VALARM 3302 TRIGGER:-PT30M 3303 REPEAT:2 3304 DURATION:PT15M 3305 ACTION:DISPLAY 3306 DESCRIPTION:Breakfast meeting with executive\n 3307 team at 8:30 AM EST. 3308 END:VALARM 3310 The following example is for a "VALARM" calendar component that 3311 specifies an email alarm that will trigger 2 days before the 3312 scheduled due date/time of a to-do it is associated with. It does 3313 not repeat. The email has a subject, body and attachment link. 3315 BEGIN:VALARM 3316 TRIGGER:-P2D 3317 ACTION:EMAIL 3318 ATTENDEE:MAILTO:john_doe@example.com 3319 SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING *** 3320 DESCRIPTION:A draft agenda needs to be sent out to the attendees 3321 to the weekly managers meeting (MGR-LIST). Attached is a 3322 pointer the document template for the agenda file. 3323 ATTACH;FMTTYPE=application/msword:http://example.com/ 3324 templates/agenda.doc 3325 END:VALARM 3327 The following example is for a "VALARM" calendar component that 3328 specifies a procedural alarm that will trigger at a precise date/ 3329 time and will repeat 23 more times at one hour intervals. The 3330 alarm will invoke a procedure file. 3332 BEGIN:VALARM 3333 TRIGGER;VALUE=DATE-TIME:19980101T050000Z 3334 REPEAT:23 3335 DURATION:PT1H 3336 ACTION:PROCEDURE 3337 ATTACH;FMTTYPE=application/octet-stream:ftp://example.com/novo- 3338 procs/felizano.exe 3339 END:VALARM 3341 3.7. Calendar Properties 3343 The Calendar Properties are attributes that apply to the iCalendar 3344 object, as a whole. These properties do not appear within a calendar 3345 component. They SHOULD be specified after the "BEGIN:VCALENDAR" 3346 delimiter string and prior to any calendar component. 3348 3.7.1. Calendar Scale 3350 Property Name: CALSCALE 3352 Purpose: This property defines the calendar scale used for the 3353 calendar information specified in the iCalendar object. 3355 Value Type: TEXT 3357 Property Parameters: Non-standard property parameters can be 3358 specified on this property. 3360 Conformance: Property can be specified in an iCalendar object. The 3361 default value is "GREGORIAN". 3363 Description: This memo is based on the Gregorian calendar scale. The 3364 Gregorian calendar scale is assumed if this property is not 3365 specified in the iCalendar object. It is expected that other 3366 calendar scales will be defined in other specifications or by 3367 future versions of this memo. 3369 Format Definition: The property is defined by the following notation: 3371 calscale = "CALSCALE" calparam ":" calvalue CRLF 3373 calparam = *(";" xparam) 3375 calvalue = "GREGORIAN" / iana-token 3377 Example: The following is an example of this property: 3379 CALSCALE:GREGORIAN 3381 3.7.2. Method 3383 Property Name: METHOD 3385 Purpose: This property defines the iCalendar object method associated 3386 with the calendar object. 3388 Value Type: TEXT 3390 Property Parameters: Non-standard property parameters can be 3391 specified on this property. 3393 Conformance: The property can be specified in an iCalendar object. 3395 Description: When used in a MIME message entity, the value of this 3396 property MUST be the same as the Content-Type "method" parameter 3397 value. This property can only appear once within the iCalendar 3398 object. If either the "METHOD" property or the Content-Type 3399 "method" parameter is specified, then the other MUST also be 3400 specified. 3402 No methods are defined by this specification. This is the subject 3403 of other specifications, such as the iCalendar Transport- 3404 independent Interoperability Protocol (iTIP) defined by [I-D.ietf- 3405 calsify-2446bis]. 3407 If this property is not present in the iCalendar object, then a 3408 scheduling transaction MUST NOT be assumed. In such cases, the 3409 iCalendar object is merely being used to transport a snapshot of 3410 some calendar information; without the intention of conveying a 3411 scheduling semantic. 3413 Format Definition: The property is defined by the following notation: 3415 method = "METHOD" metparam ":" metvalue CRLF 3417 metparam = *(";" xparam) 3419 metvalue = iana-token 3421 Example: The following is a hypothetical example of this property to 3422 convey that the iCalendar object is a request for a meeting: 3424 METHOD:REQUEST 3426 3.7.3. Product Identifier 3428 Property Name: PRODID 3430 Purpose: This property specifies the identifier for the product that 3431 created the iCalendar object. 3433 Value Type: TEXT 3435 Property Parameters: Non-standard property parameters can be 3436 specified on this property. 3438 Conformance: The property MUST be specified once in an iCalendar 3439 object. 3441 Description: The vendor of the implementation SHOULD assure that this 3442 is a globally unique identifier; using some technique such as an 3443 FPI value, as defined in [ISO.9070.1991]. 3445 This property SHOULD not be used to alter the interpretation of an 3446 iCalendar object beyond the semantics specified in this memo. For 3447 example, it is not to be used to further the understanding of non- 3448 standard properties. 3450 Format Definition: The property is defined by the following notation: 3452 prodid = "PRODID" pidparam ":" pidvalue CRLF 3454 pidparam = *(";" xparam) 3456 pidvalue = text 3457 ;Any text that describes the product and version 3458 ;and that is generally assured of being unique. 3460 Example: The following is an example of this property. It does not 3461 imply that English is the default language. 3463 PRODID:-//ABC Corporation//NONSGML My Product//EN 3465 3.7.4. Version 3467 Property Name: VERSION 3469 Purpose: This property specifies the identifier corresponding to the 3470 highest version number or the minimum and maximum range of the 3471 iCalendar specification that is required in order to interpret the 3472 iCalendar object. 3474 Value Type: TEXT 3476 Property Parameters: Non-standard property parameters can be 3477 specified on this property. 3479 Conformance: This property MUST be specified by an iCalendar object, 3480 but MUST only be specified once. 3482 Description: A value of "2.0" corresponds to this memo. 3484 Format Definition: The property is defined by the following notation: 3486 version = "VERSION" verparam ":" vervalue CRLF 3488 verparam = *(";" xparam) 3490 vervalue = "2.0" ;This memo 3491 / maxver 3492 / (minver ";" maxver) 3494 minver = 3495 ;Minimum iCalendar version needed to parse the iCalendar object 3497 maxver = 3498 ;Maximum iCalendar version needed to parse the iCalendar object 3500 Example: The following is an example of this property: 3502 VERSION:2.0 3504 3.8. Component Properties 3506 The following properties can appear within calendar components, as 3507 specified by each component property definition. 3509 3.8.1. Descriptive Component Properties 3511 The following properties specify descriptive information about 3512 calendar components. 3514 3.8.1.1. Attachment 3516 Property Name: ATTACH 3518 Purpose: The property provides the capability to associate a document 3519 object with a calendar component. 3521 Value Type: The default value type for this property is URI. The 3522 value type can also be set to BINARY to indicate inline binary 3523 encoded content information. 3525 Property Parameters: Non-standard, inline encoding, format type and 3526 value data type property parameters can be specified on this 3527 property. 3529 Conformance: The property can be specified in a "VEVENT", "VTODO", 3530 "VJOURNAL" or "VALARM" calendar components. 3532 Description: The property can be specified within "VEVENT", "VTODO", 3533 "VJOURNAL", or "VALARM" calendar components. This property can be 3534 specified multiple times within an iCalendar object. 3536 Format Definition: The property is defined by the following notation: 3538 attach = "ATTACH" attparam ":" uri CRLF 3540 attach =/ "ATTACH" attparam ";" "ENCODING" "=" "BASE64" 3541 ";" "VALUE" "=" "BINARY" ":" binary 3543 attparam = *( 3545 ; the following is optional, 3546 ; but MUST NOT occur more than once 3548 (";" fmttypeparam) / 3550 ; the following is optional, 3551 ; and MAY occur more than once 3553 (";" xparam) 3555 ) 3557 Example: The following are examples of this property: 3559 ATTACH:CID:jsmith.part3.960817T083000.xyzMail@example.com 3561 ATTACH;FMTTYPE=application/postscript:ftp://example.com/pub/ 3562 reports/r-960812.ps 3564 3.8.1.2. Categories 3566 Property Name: CATEGORIES 3568 Purpose: This property defines the categories for a calendar 3569 component. 3571 Value Type: TEXT 3573 Property Parameters: Non-standard and language property parameters 3574 can be specified on this property. 3576 Conformance: The property can be specified within "VEVENT", "VTODO" 3577 or "VJOURNAL" calendar components. 3579 Description: This property is used to specify categories or subtypes 3580 of the calendar component. The categories are useful in searching 3581 for a calendar component of a particular type and category. 3582 Within the "VEVENT", "VTODO" or "VJOURNAL" calendar components, 3583 more than one category can be specified as a list of categories 3584 separated by the COMMA character (US-ASCII decimal 44). 3586 Format Definition: The property is defined by the following notation: 3588 categories = "CATEGORIES" catparam ":" text *("," text) 3589 CRLF 3591 catparam = *( 3593 ; the following is optional, 3594 ; but MUST NOT occur more than once 3596 (";" languageparam ) / 3598 ; the following is optional, 3599 ; and MAY occur more than once 3601 (";" xparam) 3603 ) 3605 Example: The following are examples of this property: 3607 CATEGORIES:APPOINTMENT,EDUCATION 3609 CATEGORIES:MEETING 3611 3.8.1.3. Classification 3613 Property Name: CLASS 3615 Purpose: This property defines the access classification for a 3616 calendar component. 3618 Value Type: TEXT 3620 Property Parameters: Non-standard property parameters can be 3621 specified on this property. 3623 Conformance: The property can be specified once in a "VEVENT", 3624 "VTODO" or "VJOURNAL" calendar components. 3626 Description: An access classification is only one component of the 3627 general security system within a calendar application. It 3628 provides a method of capturing the scope of the access the 3629 calendar owner intends for information within an individual 3630 calendar entry. The access classification of an individual 3631 iCalendar component is useful when measured along with the other 3632 security components of a calendar system (e.g., calendar user 3633 authentication, authorization, access rights, access role, etc.). 3635 Hence, the semantics of the individual access classifications 3636 cannot be completely defined by this memo alone. Additionally, 3637 due to the "blind" nature of most exchange processes using this 3638 memo, these access classifications cannot serve as an enforcement 3639 statement for a system receiving an iCalendar object. Rather, 3640 they provide a method for capturing the intention of the calendar 3641 owner for the access to the calendar component. 3643 Format Definition: The property is defined by the following notation: 3645 class = "CLASS" classparam ":" classvalue CRLF 3647 classparam = *(";" xparam) 3649 classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token 3650 / x-name 3651 ;Default is PUBLIC 3653 Example: The following is an example of this property: 3655 CLASS:PUBLIC 3657 3.8.1.4. Comment 3659 Property Name: COMMENT 3661 Purpose: This property specifies non-processing information intended 3662 to provide a comment to the calendar user. 3664 Value Type: TEXT 3666 Property Parameters: Non-standard, alternate text representation and 3667 language property parameters can be specified on this property. 3669 Conformance: This property can be specified in "VEVENT", "VTODO", 3670 "VJOURNAL", "VTIMEZONE" or "VFREEBUSY" calendar components. 3672 Description: The property can be specified multiple times. 3674 Format Definition: The property is defined by the following notation: 3676 comment = "COMMENT" commparam ":" text CRLF 3678 commparam = *( 3680 ; the following are optional, 3681 ; but MUST NOT occur more than once 3683 (";" altrepparam) / (";" languageparam) / 3685 ; the following is optional, 3686 ; and MAY occur more than once 3688 (";" xparam) 3690 ) 3692 Example: The following is an example of this property: 3694 COMMENT:The meeting really needs to include both ourselves 3695 and the customer. We can't hold this meeting without them. 3696 As a matter of fact\, the venue for the meeting ought to be at 3697 their site. - - John 3699 3.8.1.5. Description 3701 Property Name: DESCRIPTION 3703 Purpose: This property provides a more complete description of the 3704 calendar component, than that provided by the "SUMMARY" property. 3706 Value Type: TEXT 3708 Property Parameters: Non-standard, alternate text representation and 3709 language property parameters can be specified on this property. 3711 Conformance: The property can be specified in the "VEVENT", "VTODO", 3712 "VJOURNAL" or "VALARM" calendar components. The property can be 3713 specified multiple times only within a "VJOURNAL" calendar 3714 component. 3716 Description: This property is used in the "VEVENT" and "VTODO" to 3717 capture lengthy textual decriptions associated with the activity. 3719 This property is used in the "VJOURNAL" calendar component to 3720 capture one more textual journal entries. 3722 This property is used in the "VALARM" calendar component to 3723 capture the display text for a DISPLAY category of alarm, to 3724 capture the body text for an EMAIL category of alarm and to 3725 capture the argument string for a PROCEDURE category of alarm. 3727 Format Definition: The property is defined by the following notation: 3729 description = "DESCRIPTION" descparam ":" text CRLF 3731 descparam = *( 3733 ; the following are optional, 3734 ; but MUST NOT occur more than once 3736 (";" altrepparam) / (";" languageparam) / 3738 ; the following is optional, 3739 ; and MAY occur more than once 3741 (";" xparam) 3743 ) 3745 Example: The following is an example of the property with formatted 3746 line breaks in the property value: 3748 DESCRIPTION:Meeting to provide technical review for "Phoenix" 3749 design.\nHappy Face Conference Room. Phoenix design team 3750 MUST attend this meeting.\nRSVP to team leader. 3752 The following is an example of the property with folding of long 3753 lines: 3755 DESCRIPTION:Last draft of the new novel is to be completed 3756 for the editor's proof today. 3758 3.8.1.6. Geographic Position 3760 Property Name: GEO 3762 Purpose: This property specifies information related to the global 3763 position for the activity specified by a calendar component. 3765 Value Type: FLOAT. The value MUST be two SEMICOLON separated FLOAT 3766 values. 3768 Property Parameters: Non-standard property parameters can be 3769 specified on this property. 3771 Conformance: This property can be specified in "VEVENT" or "VTODO" 3772 calendar components. 3774 Description: The property value specifies latitude and longitude, in 3775 that order (i.e., "LAT LON" ordering). The longitude represents 3776 the location east or west of the prime meridian as a positive or 3777 negative real number, respectively. The longitude and latitude 3778 values MAY be specified up to six decimal places, which will allow 3779 for accuracy to within one meter of geographical position. 3780 Receiving applications MUST accept values of this precision and 3781 MAY truncate values of greater precision. 3783 Values for latitude and longitude shall be expressed as decimal 3784 fractions of degrees. Whole degrees of latitude shall be 3785 represented by a two-digit decimal number ranging from 0 through 3786 90. Whole degrees of longitude shall be represented by a decimal 3787 number ranging from 0 through 180. When a decimal fraction of a 3788 degree is specified, it shall be separated from the whole number 3789 of degrees by a decimal point. 3791 Latitudes north of the equator shall be specified by a plus sign 3792 (+), or by the absence of a minus sign (-), preceding the digits 3793 designating degrees. Latitudes south of the Equator shall be 3794 designated by a minus sign (-) preceding the digits designating 3795 degrees. A point on the Equator shall be assigned to the Northern 3796 Hemisphere. 3798 Longitudes east of the prime meridian shall be specified by a plus 3799 sign (+), or by the absence of a minus sign (-), preceding the 3800 digits designating degrees. Longitudes west of the meridian shall 3801 be designated by minus sign (-) preceding the digits designating 3802 degrees. A point on the prime meridian shall be assigned to the 3803 Eastern Hemisphere. A point on the 180th meridian shall be 3804 assigned to the Western Hemisphere. One exception to this last 3805 convention is permitted. For the special condition of describing 3806 a band of latitude around the earth, the East Bounding Coordinate 3807 data element shall be assigned the value +180 (180) degrees. 3809 Any spatial address with a latitude of +90 (90) or -90 degrees 3810 will specify the position at the North or South Pole, 3811 respectively. The component for longitude may have any legal 3812 value. 3814 With the exception of the special condition described above, this 3815 form is specified in Department of Commerce, 1986, Representation 3816 of geographic point locations for information interchange (Federal 3817 Information Processing Standard 70-1): Washington, Department of 3818 Commerce, National Institute of Standards and Technology. 3820 The simple formula for converting degrees-minutes-seconds into 3821 decimal degrees is: 3823 decimal = degrees + minutes/60 + seconds/3600. 3825 Format Definition: The property is defined by the following notation: 3827 geo = "GEO" geoparam ":" geovalue CRLF 3829 geoparam = *(";" xparam) 3831 geovalue = float ";" float 3832 ;Latitude and Longitude components 3834 Example: The following is an example of this property: 3836 GEO:37.386013;-122.082932 3838 3.8.1.7. Location 3840 Property Name: LOCATION 3842 Purpose: The property defines the intended venue for the activity 3843 defined by a calendar component. 3845 Value Type: TEXT 3847 Property Parameters: Non-standard, alternate text representation and 3848 language property parameters can be specified on this property. 3850 Conformance: This property can be specified in "VEVENT" or "VTODO" 3851 calendar component. 3853 Description: Specific venues such as conference or meeting rooms may 3854 be explicitly specified using this property. An alternate 3855 representation may be specified that is a URI that points to 3856 directory information with more structured specification of the 3857 location. For example, the alternate representation may specify 3858 either an LDAP URI pointing to an LDAP server entry or a CID URI 3859 pointing to a MIME body part containing a vCard [RFC2426] for the 3860 location. 3862 Format Definition: The property is defined by the following notation: 3864 location = "LOCATION locparam ":" text CRLF 3866 locparam = *( 3868 ; the following are optional, 3869 ; but MUST NOT occur more than once 3871 (";" altrepparam) / (";" languageparam) / 3873 ; the following is optional, 3874 ; and MAY occur more than once 3876 (";" xparam) 3878 ) 3880 Example: The following are some examples of this property: 3882 LOCATION:Conference Room - F123\, Bldg. 002 3884 LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf": 3885 Conference Room - F123\, Bldg. 002 3887 3.8.1.8. Percent Complete 3889 Property Name: PERCENT-COMPLETE 3891 Purpose: This property is used by an assignee or delegatee of a to-do 3892 to convey the percent completion of a to-do to the Organizer. 3894 Value Type: INTEGER 3896 Property Parameters: Non-standard property parameters can be 3897 specified on this property. 3899 Conformance: This property can be specified in a "VTODO" calendar 3900 component. 3902 Description: The property value is a positive integer between zero 3903 and one hundred. A value of "0" indicates the to-do has not yet 3904 been started. A value of "100" indicates that the to-do has been 3905 completed. Integer values in between indicate the percent 3906 partially complete. 3908 When a to-do is assigned to multiple individuals, the property 3909 value indicates the percent complete for that portion of the to-do 3910 assigned to the assignee or delegatee. For example, if a to-do is 3911 assigned to both individuals "A" and "B". A reply from "A" with a 3912 percent complete of "70" indicates that "A" has completed 70% of 3913 the to-do assigned to them. A reply from "B" with a percent 3914 complete of "50" indicates "B" has completed 50% of the to-do 3915 assigned to them. 3917 Format Definition: The property is defined by the following notation: 3919 percent = "PERCENT-COMPLETE" pctparam ":" integer CRLF 3921 pctparam = *(";" xparam) 3923 Example: The following is an example of this property to show 39% 3924 completion: 3926 PERCENT-COMPLETE:39 3928 3.8.1.9. Priority 3930 Property Name: PRIORITY 3932 Purpose: The property defines the relative priority for a calendar 3933 component. 3935 Value Type: INTEGER 3937 Property Parameters: Non-standard property parameters can be 3938 specified on this property. 3940 Conformance: The property can be specified in a "VEVENT" or "VTODO" 3941 calendar component. 3943 Description: The priority is specified as an integer in the range 3944 zero to nine. A value of zero (US-ASCII decimal 48) specifies an 3945 undefined priority. A value of one (US-ASCII decimal 49) is the 3946 highest priority. A value of two (US-ASCII decimal 50) is the 3947 second highest priority. Subsequent numbers specify a decreasing 3948 ordinal priority. A value of nine (US-ASCII decimal 57 ) is the 3949 lowest priority. 3951 A CUA with a three-level priority scheme of "HIGH", "MEDIUM" and 3952 "LOW" is mapped into this property such that a property value in 3953 the range of one (US-ASCII decimal 49) to four (US-ASCII decimal 3954 52) specifies "HIGH" priority. A value of five (US-ASCII decimal 3955 53) is the normal or "MEDIUM" priority. A value in the range of 3956 six (US-ASCII decimal 54) to nine (US-ASCII decimal 57 ) is "LOW" 3957 priority. 3959 A CUA with a priority schema of "A1", "A2", "A3", "B1", "B2", ..., 3960 "C3" is mapped into this property such that a property value of 3961 one (US-ASCII decimal 49) specifies "A1", a property value of two 3962 (US-ASCII decimal 50) specifies "A2", a property value of three 3963 (US-ASCII decimal 51) specifies "A3", and so forth up to a 3964 property value of 9 (US-ASCII decimal 57 ) specifies "C3". 3966 Other integer values are reserved for future use. 3968 Within a "VEVENT" calendar component, this property specifies a 3969 priority for the event. This property may be useful when more 3970 than one event is scheduled for a given time period. 3972 Within a "VTODO" calendar component, this property specified a 3973 priority for the to-do. This property is useful in prioritizing 3974 multiple action items for a given time period. 3976 Format Definition: The property is defined by the following notation: 3978 priority = "PRIORITY" prioparam ":" privalue CRLF 3979 ;Default is zero 3981 prioparam = *(";" xparam) 3983 privalue = integer ;Must be in the range [0..9] 3984 ; All other values are reserved for future use 3986 Example: The following is an example of a property with the highest 3987 priority: 3989 PRIORITY:1 3991 The following is an example of a property with a next highest 3992 priority: 3994 PRIORITY:2 3996 The following is an example of a property with no priority. This 3997 is equivalent to not specifying the "PRIORITY" property: 3999 PRIORITY:0 4001 3.8.1.10. Resources 4003 Property Name: RESOURCES 4005 Purpose: This property defines the equipment or resources anticipated 4006 for an activity specified by a calendar entity.. 4008 Value Type: TEXT 4010 Property Parameters: Non-standard, alternate text representation and 4011 language property parameters can be specified on this property. 4013 Conformance: This property can be specified in "VEVENT" or "VTODO" 4014 calendar component. 4016 Description: The property value is an arbitrary text. More than one 4017 resource can be specified as a list of resources separated by the 4018 COMMA character (US-ASCII decimal 44). 4020 Format Definition: The property is defined by the following notation: 4022 resources = "RESOURCES" resrcparam ":" text *("," text) CRLF 4024 resrcparam = *( 4026 ; the following are optional, 4027 ; but MUST NOT occur more than once 4029 (";" altrepparam) / (";" languageparam) / 4031 ; the following is optional, 4032 ; and MAY occur more than once 4034 (";" xparam) 4036 ) 4038 Example: The following is an example of this property: 4040 RESOURCES:EASEL,PROJECTOR,VCR 4042 RESOURCES;LANGUAGE=fr:1 raton-laveur 4044 3.8.1.11. Status 4045 Property Name: STATUS 4047 Purpose: This property defines the overall status or confirmation for 4048 the calendar component. 4050 Value Type: TEXT 4052 Property Parameters: Non-standard property parameters can be 4053 specified on this property. 4055 Conformance: This property can be specified in "VEVENT", "VTODO" or 4056 "VJOURNAL" calendar components. 4058 Description: In a group scheduled calendar component, the property is 4059 used by the "Organizer" to provide a confirmation of the event to 4060 the "Attendees". For example in a "VEVENT" calendar component, 4061 the "Organizer" can indicate that a meeting is tentative, 4062 confirmed or cancelled. In a "VTODO" calendar component, the 4063 "Organizer" can indicate that an action item needs action, is 4064 completed, is in process or being worked on, or has been 4065 cancelled. In a "VJOURNAL" calendar component, the "Organizer" 4066 can indicate that a journal entry is draft, final or has been 4067 cancelled or removed. 4069 Format Definition: The property is defined by the following notation: 4071 status = "STATUS" statparam":" statvalue CRLF 4073 statparam = *(";" xparam) 4075 statvalue = "TENTATIVE" ;Indicates event is 4076 ;tentative. 4077 / "CONFIRMED" ;Indicates event is 4078 ;definite. 4079 / "CANCELLED" ;Indicates event was 4080 ;cancelled. 4081 ;Status values for a "VEVENT" 4083 statvalue = "NEEDS-ACTION" ;Indicates to-do needs action. 4084 / "COMPLETED" ;Indicates to-do completed. 4085 / "IN-PROCESS" ;Indicates to-do in process. 4086 / "CANCELLED" ;Indicates to-do was cancelled. 4087 ;Status values for "VTODO". 4089 statvalue = "DRAFT" ;Indicates journal is draft. 4090 / "FINAL" ;Indicates journal is final. 4091 / "CANCELLED" ;Indicates journal is removed. 4092 ;Status values for "VJOURNAL". 4094 Example: The following is an example of this property for a "VEVENT" 4095 calendar component: 4097 STATUS:TENTATIVE 4099 The following is an example of this property for a "VTODO" 4100 calendar component: 4102 STATUS:NEEDS-ACTION 4104 The following is an example of this property for a "VJOURNAL" 4105 calendar component: 4107 STATUS:DRAFT 4109 3.8.1.12. Summary 4111 Property Name: SUMMARY 4113 Purpose: This property defines a short summary or subject for the 4114 calendar component. 4116 Value Type: TEXT 4118 Property Parameters: Non-standard, alternate text representation and 4119 language property parameters can be specified on this property. 4121 Conformance: The property can be specified in "VEVENT", "VTODO", 4122 "VJOURNAL" or "VALARM" calendar components. 4124 Description: This property is used in the "VEVENT", "VTODO" and 4125 "VJOURNAL" calendar components to capture a short, one line 4126 summary about the activity or journal entry. 4128 This property is used in the "VALARM" calendar component to 4129 capture the subject of an EMAIL category of alarm. 4131 Format Definition: The property is defined by the following notation: 4133 summary = "SUMMARY" summparam ":" text CRLF 4135 summparam = *( 4137 ; the following are optional, 4138 ; but MUST NOT occur more than once 4140 (";" altrepparam) / (";" languageparam) / 4142 ; the following is optional, 4143 ; and MAY occur more than once 4145 (";" xparam) 4147 ) 4149 Example: The following is an example of this property: 4151 SUMMARY:Department Party 4153 3.8.2. Date and Time Component Properties 4155 The following properties specify date and time related information in 4156 calendar components. 4158 3.8.2.1. Date/Time Completed 4160 Property Name: COMPLETED 4162 Purpose: This property defines the date and time that a to-do was 4163 actually completed. 4165 Value Type: DATE-TIME 4167 Property Parameters: Non-standard property parameters can be 4168 specified on this property. 4170 Conformance: The property can be specified in a "VTODO" calendar 4171 component. 4173 Description: The date and time MUST be in a UTC format. 4175 Format Definition: The property is defined by the following notation: 4177 completed = "COMPLETED" compparam ":" date-time CRLF 4179 compparam = *(";" xparam) 4181 Example: The following is an example of this property: 4183 COMPLETED:19960401T235959Z 4185 3.8.2.2. Date/Time End 4187 Property Name: DTEND 4189 Purpose: This property specifies the date and time that a calendar 4190 component ends. 4192 Value Type: The default value type is DATE-TIME. The value type can 4193 be set to a DATE value type. 4195 Property Parameters: Non-standard, value data type, time zone 4196 identifier property parameters can be specified on this property. 4198 Conformance: This property can be specified in "VEVENT" or 4199 "VFREEBUSY" calendar components. 4201 Description: Within the "VEVENT" calendar component, this property 4202 defines the date and time by which the event ends. The value MUST 4203 be later in time than the value of the "DTSTART" property. 4205 Within the "VFREEBUSY" calendar component, this property defines 4206 the end date and time for the free or busy time information. The 4207 time MUST be specified in the UTC time format. The value MUST be 4208 later in time than the value of the "DTSTART" property. 4210 Format Definition: The property is defined by the following notation: 4212 dtend = "DTEND" dtendparam ":" dtendval CRLF 4214 dtendparam = *( 4216 ; the following are optional, 4217 ; but MUST NOT occur more than once 4219 (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / 4220 (";" tzidparam) / 4222 ; the following is optional, 4223 ; and MAY occur more than once 4225 (";" xparam) 4227 ) 4229 dtendval = date-time / date 4230 ;Value MUST match value type 4232 Example: The following is an example of this property: 4234 DTEND:19960401T235959Z 4236 DTEND;VALUE=DATE:19980704 4238 3.8.2.3. Date/Time Due 4240 Property Name: DUE 4242 Purpose: This property defines the date and time that a to-do is 4243 expected to be completed. 4245 Value Type: The default value type is DATE-TIME. The value type can 4246 be set to a DATE value type. 4248 Property Parameters: Non-standard, value data type, time zone 4249 identifier property parameters can be specified on this property. 4251 Conformance: The property can be specified once in a "VTODO" calendar 4252 component. 4254 Description: The value MUST be a date/time equal to or after the 4255 DTSTART value, if specified. 4257 Format Definition: The property is defined by the following notation: 4259 due = "DUE" dueparam ":" dueval CRLF 4261 dueparam = *( 4262 ; the following are optional, 4263 ; but MUST NOT occur more than once 4265 (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / 4266 (";" tzidparam) / 4268 ; the following is optional, 4269 ; and MAY occur more than once 4271 *(";" xparam) 4273 ) 4275 dueval = date-time / date 4276 ;Value MUST match value type 4278 Example: The following is an example of this property: 4280 DUE:19980430T235959Z 4282 3.8.2.4. Date/Time Start 4284 Property Name: DTSTART 4286 Purpose: This property specifies when the calendar component begins. 4288 Value Type: The default value type is DATE-TIME. The time value MUST 4289 be one of the forms defined for the DATE-TIME value type. The 4290 value type can be set to a DATE value type. 4292 Property Parameters: Non-standard, value data type, time zone 4293 identifier property parameters can be specified on this property. 4295 Conformance: This property can be specified in the "VEVENT", "VTODO", 4296 "VFREEBUSY", or "VTIMEZONE" calendar components. This property is 4297 REQUIRED in "VEVENT" calendar components. 4299 Description: Within the "VEVENT" calendar component, this property 4300 defines the start date and time for the event. Events can have a 4301 start date/time but no end date/time. In that case, the event 4302 does not take up any time. 4304 Within the "VFREEBUSY" calendar component, this property defines 4305 the start date and time for the free or busy time information. 4306 The time MUST be specified in UTC time. 4308 Within the "VTIMEZONE" calendar component, this property defines 4309 the effective start date and time for a time zone specification. 4310 This property is REQUIRED within each STANDARD and DAYLIGHT part 4311 included in "VTIMEZONE" calendar components and MUST be specified 4312 as a local DATE-TIME without the "TZID" property parameter. 4314 Format Definition: The property is defined by the following notation: 4316 dtstart = "DTSTART" dtstparam ":" dtstval CRLF 4318 dtstparam = *( 4320 ; the following are optional, 4321 ; but MUST NOT occur more than once 4323 (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / 4324 (";" tzidparam) / 4326 ; the following is optional, 4327 ; and MAY occur more than once 4329 *(";" xparam) 4331 ) 4333 dtstval = date-time / date 4334 ;Value MUST match value type 4336 Example: The following is an example of this property: 4338 DTSTART:19980118T073000Z 4340 3.8.2.5. Duration 4342 Property Name: DURATION 4344 Purpose: The property specifies a positive duration of time. 4346 Value Type: DURATION 4348 Property Parameters: Non-standard property parameters can be 4349 specified on this property. 4351 Conformance: The property can be specified in "VEVENT", "VTODO", 4352 "VFREEBUSY" or "VALARM" calendar components. 4354 Description: In a "VEVENT" calendar component the property may be 4355 used to specify a duration of the event, instead of an explicit 4356 end date/time. In a "VTODO" calendar component the property may 4357 be used to specify a duration for the to-do, instead of an 4358 explicit due date/time. In a "VFREEBUSY" calendar component the 4359 property may be used to specify the interval of free time being 4360 requested. In a "VALARM" calendar component the property may be 4361 used to specify the delay period prior to repeating an alarm. 4363 Format Definition: The property is defined by the following notation: 4365 duration = "DURATION" durparam ":" dur-value CRLF 4366 ;consisting of a positive duration of time. 4368 durparam = *(";" xparam) 4370 Example: The following is an example of this property that specifies 4371 an interval of time of 1 hour and zero minutes and zero seconds: 4373 DURATION:PT1H0M0S 4375 The following is an example of this property that specifies an 4376 interval of time of 15 minutes. 4378 DURATION:PT15M 4380 3.8.2.6. Free/Busy Time 4382 Property Name: FREEBUSY 4384 Purpose: The property defines one or more free or busy time 4385 intervals. 4387 Value Type: PERIOD. The date and time values MUST be in a UTC time 4388 format. 4390 Property Parameters: Non-standard or free/busy time type property 4391 parameters can be specified on this property. 4393 Conformance: The property can be specified in a "VFREEBUSY" calendar 4394 component. 4396 Description: These time periods can be specified as either a start 4397 and end date-time or a start date-time and duration. The date and 4398 time MUST be a UTC time format. 4400 "FREEBUSY" properties within the "VFREEBUSY" calendar component 4401 SHOULD be sorted in ascending order, based on start time and then 4402 end time, with the earliest periods first. 4404 The "FREEBUSY" property can specify more than one value, separated 4405 by the COMMA character (US-ASCII decimal 44). In such cases, the 4406 "FREEBUSY" property values SHOULD all be of the same "FBTYPE" 4407 property parameter type (e.g., all values of a particular "FBTYPE" 4408 listed together in a single property). 4410 Format Definition: The property is defined by the following notation: 4412 freebusy = "FREEBUSY" fbparam ":" fbvalue CRLF 4414 fbparam = *( 4415 ; the following is optional, 4416 ; but MUST NOT occur more than once 4418 (";" fbtypeparam) / 4420 ; the following is optional, 4421 ; and MAY occur more than once 4423 (";" xparam) 4425 ) 4427 fbvalue = period *("," period 4428 ;Time value MUST be in the UTC time format. 4430 Example: The following are some examples of this property: 4432 FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M 4434 FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H 4436 FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H 4437 ,19970308T230000Z/19970309T000000Z 4439 3.8.2.7. Time Transparency 4440 Property Name: TRANSP 4442 Purpose: This property defines whether an event is transparent or not 4443 to busy time searches. 4445 Value Type: TEXT 4447 Property Parameters: Non-standard property parameters can be 4448 specified on this property. 4450 Conformance: This property can be specified once in a "VEVENT" 4451 calendar component. 4453 Description: Time Transparency is the characteristic of an event that 4454 determines whether it appears to consume time on a calendar. 4455 Events that consume actual time for the individual or resource 4456 associated with the calendar SHOULD be recorded as OPAQUE, 4457 allowing them to be detected by free-busy time searches. Other 4458 events, which do not take up the individual's (or resource's) time 4459 SHOULD be recorded as TRANSPARENT, making them invisible to free- 4460 busy time searches. 4462 Format Definition: The property is defined by the following notation: 4464 transp = "TRANSP" transparam ":" transvalue CRLF 4466 transparam = *(";" xparam) 4468 transvalue = "OPAQUE" 4469 ;Blocks or opaque on busy time searches. 4470 / "TRANSPARENT" 4471 ;Transparent on busy time searches. 4472 ;Default value is OPAQUE 4474 Example: The following is an example of this property for an event 4475 that is transparent or does not block on free/busy time searches: 4477 TRANSP:TRANSPARENT 4479 The following is an example of this property for an event that is 4480 opaque or blocks on free/busy time searches: 4482 TRANSP:OPAQUE 4484 3.8.3. Time Zone Component Properties 4486 The following properties specify time zone information in calendar 4487 components. 4489 3.8.3.1. Time Zone Identifier 4491 Property Name: TZID 4493 Purpose: This property specifies the text value that uniquely 4494 identifies the "VTIMEZONE" calendar component. 4496 Value Type: TEXT 4498 Property Parameters: Non-standard property parameters can be 4499 specified on this property. 4501 Conformance: This property MUST be specified in a "VTIMEZONE" 4502 calendar component. 4504 Description: This is the label by which a time zone calendar 4505 component is referenced by any iCalendar properties whose data 4506 type is either DATE-TIME or TIME and not intended to specify a UTC 4507 or a "floating" time. The presence of the SOLIDUS character (US- 4508 ASCII decimal 47) as a prefix, indicates that this TZID represents 4509 an unique ID in a globally defined time zone registry (when such 4510 registry is defined). 4512 Note: This document does not define a naming convention for 4513 time zone identifiers. Implementers may want to use the naming 4514 conventions defined in existing time zone specifications such 4515 as the public-domain Olson database [TZDB]. The specification 4516 of globally unique time zone identifiers is not addressed by 4517 this document and is left for future study. 4519 Format Definition: The property is defined by the following notation: 4521 tzid = "TZID" tzidpropparam ":" [tzidprefix] text CRLF 4523 tzidpropparam = *(";" xparam) 4525 ;tzidprefix = "/" 4526 ; Defined previously. Just listed here for reader convenience. 4528 Example: The following are examples of non-globally unique time zone 4529 identifiers: 4531 TZID:US-Eastern 4533 TZID:California-Los_Angeles 4535 The following is an example of a fictitious globally unique time 4536 zone identifier: 4538 TZID:/US-New_York-New_York 4540 3.8.3.2. Time Zone Name 4542 Property Name: TZNAME 4544 Purpose: This property specifies the customary designation for a time 4545 zone description. 4547 Value Type: TEXT 4549 Property Parameters: Non-standard and language property parameters 4550 can be specified on this property. 4552 Conformance: This property can be specified in a "VTIMEZONE" calendar 4553 component. 4555 Description: This property may be specified in multiple languages; in 4556 order to provide for different language requirements. 4558 Format Definition: The property is defined by the following notation: 4560 tzname = "TZNAME" tznparam ":" text CRLF 4562 tznparam = *( 4564 ; the following is optional, 4565 ; but MUST NOT occur more than once 4567 (";" languageparam) / 4569 ; the following is optional, 4570 ; and MAY occur more than once 4572 (";" xparam) 4574 ) 4576 Example: The following are example of this property: 4578 TZNAME:EST 4580 The following is an example of this property when two different 4581 languages for the time zone name are specified: 4583 TZNAME;LANGUAGE=en:EST 4584 TZNAME;LANGUAGE=fr-CA:HNE 4586 3.8.3.3. Time Zone Offset From 4588 Property Name: TZOFFSETFROM 4590 Purpose: This property specifies the offset which is in use prior to 4591 this time zone observance. 4593 Value Type: UTC-OFFSET 4595 Property Parameters: Non-standard property parameters can be 4596 specified on this property. 4598 Conformance: This property MUST be specified in a "VTIMEZONE" 4599 calendar component. 4601 Description: This property specifies the offset which is in use prior 4602 to this time observance. It is used to calculate the absolute 4603 time at which the transition to a given observance takes place. 4604 This property MUST only be specified in a "VTIMEZONE" calendar 4605 component. A "VTIMEZONE" calendar component MUST include this 4606 property. The property value is a signed numeric indicating the 4607 number of hours and possibly minutes from UTC. Positive numbers 4608 represent time zones east of the prime meridian, or ahead of UTC. 4609 Negative numbers represent time zones west of the prime meridian, 4610 or behind UTC. 4612 Format Definition: The property is defined by the following notation: 4614 tzoffsetfrom = "TZOFFSETFROM" frmparam ":" utc-offset 4615 CRLF 4617 frmparam = *(";" xparam) 4619 Example: The following are examples of this property: 4621 TZOFFSETFROM:-0500 4623 TZOFFSETFROM:+1345 4625 3.8.3.4. Time Zone Offset To 4627 Property Name: TZOFFSETTO 4629 Purpose: This property specifies the offset which is in use in this 4630 time zone observance. 4632 Value Type: UTC-OFFSET 4634 Property Parameters: Non-standard property parameters can be 4635 specified on this property. 4637 Conformance: This property MUST be specified in a "VTIMEZONE" 4638 calendar component. 4640 Description: This property specifies the offset which is in use in 4641 this time zone observance. It is used to calculate the absolute 4642 time for the new observance. The property value is a signed 4643 numeric indicating the number of hours and possibly minutes from 4644 UTC. Positive numbers represent time zones east of the prime 4645 meridian, or ahead of UTC. Negative numbers represent time zones 4646 west of the prime meridian, or behind UTC. 4648 Format Definition: The property is defined by the following notation: 4650 tzoffsetto = "TZOFFSETTO" toparam ":" utc-offset CRLF 4652 toparam = *(";" xparam) 4654 Example: The following are examples of this property: 4656 TZOFFSETTO:-0400 4658 TZOFFSETTO:+1245 4660 3.8.3.5. Time Zone URL 4662 Property Name: TZURL 4664 Purpose: The TZURL provides a means for a VTIMEZONE component to 4665 point to a network location that can be used to retrieve an up-to- 4666 date version of itself. 4668 Value Type: URI 4669 Property Parameters: Non-standard property parameters can be 4670 specified on this property. 4672 Conformance: This property can be specified in a "VTIMEZONE" calendar 4673 component. 4675 Description: The TZURL provides a means for a VTIMEZONE component to 4676 point to a network location that can be used to retrieve an up-to- 4677 date version of itself. This provides a hook to handle changes 4678 government bodies impose upon time zone definitions. Retrieval of 4679 this resource results in an iCalendar object containing a single 4680 VTIMEZONE component and a METHOD property set to PUBLISH. 4682 Format Definition: The property is defined by the following notation: 4684 tzurl = "TZURL" tzurlparam ":" uri CRLF 4686 tzurlparam = *(";" xparam) 4688 Example: The following is an example of this property: 4690 TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles.ics 4692 3.8.4. Relationship Component Properties 4694 The following properties specify relationship information in calendar 4695 components. 4697 3.8.4.1. Attendee 4699 Property Name: ATTENDEE 4701 Purpose: The property defines an "Attendee" within a calendar 4702 component. 4704 Value Type: CAL-ADDRESS 4706 Property Parameters: Non-standard, language, calendar user type, 4707 group or list membership, participation role, participation 4708 status, RSVP expectation, delegatee, delegator, sent by, common 4709 name or directory entry reference property parameters can be 4710 specified on this property. 4712 Conformance: This property MUST be specified in an iCalendar object 4713 that specifies a group scheduled calendar entity. This property 4714 MUST NOT be specified in an iCalendar object when publishing the 4715 calendar information (e.g., NOT in an iCalendar object that 4716 specifies the publication of a calendar user's busy time, event, 4717 to-do or journal). This property is not specified in an iCalendar 4718 object that specifies only a time zone definition or that defines 4719 calendar entities that are not group scheduled entities, but are 4720 entities only on a single user's calendar. 4722 Description: The property MUST only be specified within calendar 4723 components to specify participants, non-participants and the chair 4724 of a group scheduled calendar entity. The property is specified 4725 within an "EMAIL" category of the "VALARM" calendar component to 4726 specify an email address that is to receive the email type of 4727 iCalendar alarm. 4729 The property parameter CN is for the common or displayable name 4730 associated with the calendar address; ROLE, for the intended role 4731 that the attendee will have in the calendar component; PARTSTAT, 4732 for the status of the attendee's participation; RSVP, for 4733 indicating whether the favor of a reply is requested; CUTYPE, to 4734 indicate the type of calendar user; MEMBER, to indicate the groups 4735 that the attendee belongs to; DELEGATED-TO, to indicate the 4736 calendar users that the original request was delegated to; and 4737 DELEGATED-FROM, to indicate whom the request was delegated from; 4738 SENT-BY, to indicate whom is acting on behalf of the ATTENDEE; and 4739 DIR, to indicate the URI that points to the directory information 4740 corresponding to the attendee. These property parameters can be 4741 specified on an "ATTENDEE" property in either a "VEVENT", "VTODO" 4742 or "VJOURNAL" calendar component. They MUST NOT be specified in 4743 an "ATTENDEE" property in a "VFREEBUSY" or "VALARM" calendar 4744 component. If the LANGUAGE property parameter is specified, the 4745 identified language applies to the CN parameter. 4747 A recipient delegated a request MUST inherit the RSVP and ROLE 4748 values from the attendee that delegated the request to them. 4750 Multiple attendees can be specified by including multiple 4751 "ATTENDEE" properties within the calendar component. 4753 Format Definition: The property is defined by the following notation: 4755 attendee = "ATTENDEE" attparam ":" cal-address CRLF 4757 attparam = *( 4759 ; the following are optional, 4760 ; but MUST NOT occur more than once 4762 (";" cutypeparam) / (";"memberparam) / 4763 (";" roleparam) / (";" partstatparam) / 4764 (";" rsvpparam) / (";" deltoparam) / 4765 (";" delfromparam) / (";" sentbyparam) / 4766 (";"cnparam) / (";" dirparam) / 4767 (";" languageparam) / 4769 ; the following is optional, 4770 ; and MAY occur more than once 4772 (";" xparam) 4774 ) 4776 Example: The following are examples of this property's use for a 4777 to-do: 4779 ORGANIZER:MAILTO:jsmith@example.com 4780 ATTENDEE;MEMBER="MAILTO:DEV-GROUP@example.com": 4781 MAILTO:joecool@example.com 4782 ATTENDEE;DELEGATED-FROM="MAILTO:immud@example.com": 4783 MAILTO:ildoit@example.com 4785 The following is an example of this property used for specifying 4786 multiple attendees to an event: 4788 ORGANIZER:MAILTO:jsmith@example.com 4789 ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;CN=Henry 4790 Cabot:MAILTO:hcabot@example.com 4791 ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="MAILTO:bob@ 4792 example.com" 4793 ;PARTSTAT=ACCEPTED;CN=Jane Doe:MAILTO:jdoe@example.com 4795 The following is an example of this property with a URI to the 4796 directory information associated with the attendee: 4798 ATTENDEE;CN=John Smith;DIR="ldap://example.com:6666/o=ABC% 4799 20Industries,c=US???(cn=Jim%20Dolittle)":MAILTO:jimdo@ 4800 example.com 4802 The following is an example of this property with "delegatee" and 4803 "delegator" information for an event: 4805 ORGANIZER;CN=John Smith:MAILTO:jsmith@example.com 4806 ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;DELEGATED-FROM= 4807 "MAILTO:iamboss@example.com";CN=Henry Cabot:MAILTO:hcabot@ 4808 example.com 4809 ATTENDEE;ROLE=NON-PARTICIPANT;PARTSTAT=DELEGATED;DELEGATED-TO= 4810 "MAILTO:hcabot@example.com";CN=The Big Cheese:MAILTO:iamboss 4811 @example.com 4812 ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=Jane Doe 4813 :MAILTO:jdoe@example.com 4815 Example: The following is an example of this property's use when 4816 another calendar user is acting on behalf of the "Attendee": 4818 ATTENDEE;SENT-BY=MAILTO:jan_doe@example.com;CN=John Smith:MAILTO: 4819 jsmith@example.com 4821 3.8.4.2. Contact 4823 Property Name: CONTACT 4825 Purpose: The property is used to represent contact information or 4826 alternately a reference to contact information associated with the 4827 calendar component. 4829 Value Type: TEXT 4831 Property Parameters: Non-standard, alternate text representation and 4832 language property parameters can be specified on this property. 4834 Conformance: The property can be specified in a "VEVENT", "VTODO", 4835 "VJOURNAL" or "VFREEBUSY" calendar component. 4837 Description: The property value consists of textual contact 4838 information. An alternative representation for the property value 4839 can also be specified that refers to a URI pointing to an 4840 alternate form, such as a vCard [RFC2426], for the contact 4841 information. 4843 Format Definition: The property is defined by the following notation: 4845 contact = "CONTACT" contparam ":" text CRLF 4847 contparam = *( 4848 ; the following are optional, 4849 ; but MUST NOT occur more than once 4851 (";" altrepparam) / (";" languageparam) / 4853 ; the following is optional, 4854 ; and MAY occur more than once 4856 (";" xparam) 4858 ) 4860 Example: The following is an example of this property referencing 4861 textual contact information: 4863 CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234 4865 The following is an example of this property with an alternate 4866 representation of a LDAP URI to a directory entry containing the 4867 contact information: 4869 CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\, 4870 c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\, 4871 +1-919-555-1234 4873 The following is an example of this property with an alternate 4874 representation of a MIME body part containing the contact 4875 information, such as a vCard [RFC2426] embedded in a text/ 4876 directory media type [RFC2425] : 4878 CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com": 4879 Jim Dolittle\, ABC Industries\, +1-919-555-1234 4881 The following is an example of this property referencing a network 4882 resource, such as a vCard [RFC2426] object containing the contact 4883 information: 4885 CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim 4886 Dolittle\, ABC Industries\, +1-919-555-1234 4888 3.8.4.3. Organizer 4889 Property Name: ORGANIZER 4891 Purpose: The property defines the organizer for a calendar component. 4893 Value Type: CAL-ADDRESS 4895 Property Parameters: Non-standard, language, common name, directory 4896 entry reference, sent by property parameters can be specified on 4897 this property. 4899 Conformance: This property MUST be specified in an iCalendar object 4900 that specifies a group scheduled calendar entity. This property 4901 MUST be specified in an iCalendar object that specifies the 4902 publication of a calendar user's busy time. This property MUST 4903 NOT be specified in an iCalendar object that specifies only a time 4904 zone definition or that defines calendar entities that are not 4905 group scheduled entities, but are entities only on a single user's 4906 calendar. 4908 Description: The property is specified within the "VEVENT", "VTODO", 4909 "VJOURNAL" calendar components to specify the organizer of a group 4910 scheduled calendar entity. The property is specified within the 4911 "VFREEBUSY" calendar component to specify the calendar user 4912 requesting the free or busy time. When publishing a "VFREEBUSY" 4913 calendar component, the property is used to specify the calendar 4914 that the published busy time came from. 4916 The property has the property parameters CN, for specifying the 4917 common or display name associated with the "Organizer", DIR, for 4918 specifying a pointer to the directory information associated with 4919 the "Organizer", SENT-BY, for specifying another calendar user 4920 that is acting on behalf of the "Organizer". The non-standard 4921 parameters may also be specified on this property. If the 4922 LANGUAGE property parameter is specified, the identified language 4923 applies to the CN parameter value. 4925 Format Definition: The property is defined by the following notation: 4927 organizer = "ORGANIZER" orgparam ":" 4928 cal-address CRLF 4930 orgparam = *( 4932 ; the following are optional, 4933 ; but MUST NOT occur more than once 4935 (";" cnparam) / (";" dirparam) / (";" sentbyparam) / 4936 (";" languageparam) / 4938 ; the following is optional, 4939 ; and MAY occur more than once 4941 (";" xparam) 4943 ) 4945 Example: The following is an example of this property: 4947 ORGANIZER;CN=John Smith:MAILTO:jsmith@example.com 4949 The following is an example of this property with a pointer to the 4950 directory information associated with the organizer: 4952 ORGANIZER;CN=JohnSmith;DIR="ldap://example.com:6666/o=DC%20Ass 4953 ociates,c=US???(cn=John%20Smith)":MAILTO:jsmith@example.com 4955 The following is an example of this property used by another 4956 calendar user who is acting on behalf of the organizer, with 4957 responses intended to be sent back to the organizer, not the other 4958 calendar user: 4960 ORGANIZER;SENT-BY="MAILTO:jane_doe@example.com": 4961 MAILTO:jsmith@example.com 4963 3.8.4.4. Recurrence ID 4965 Property Name: RECURRENCE-ID 4967 Purpose: This property is used in conjunction with the "UID" and 4968 "SEQUENCE" property to identify a specific instance of a recurring 4969 "VEVENT", "VTODO" or "VJOURNAL" calendar component. The property 4970 value is the effective value of the "DTSTART" property of the 4971 recurrence instance. 4973 Value Type: The default value type for this property is DATE-TIME. 4974 The time format can be any of the valid forms defined for a DATE- 4975 TIME value type. See DATE-TIME value type definition for specific 4976 interpretations of the various forms. The value type can be set 4977 to DATE. 4979 Property Parameters: Non-standard property, value data type, time 4980 zone identifier and recurrence identifier range parameters can be 4981 specified on this property. 4983 Conformance: This property can be specified in an iCalendar object 4984 containing a recurring calendar component. 4986 Description: The full range of calendar components specified by a 4987 recurrence set is referenced by referring to just the "UID" 4988 property value corresponding to the calendar component. The 4989 "RECURRENCE-ID" property allows the reference to an individual 4990 instance within the recurrence set. 4992 If the value of the "DTSTART" property is a DATE type value, then 4993 the value MUST be the calendar date for the recurrence instance. 4995 The date/time value is set to the time when the original 4996 recurrence instance would occur; meaning that if the intent is to 4997 change a Friday meeting to Thursday, the date/time is still set to 4998 the original Friday meeting. 5000 The "RECURRENCE-ID" property is used in conjunction with the "UID" 5001 and "SEQUENCE" property to identify a particular instance of a 5002 recurring event, to-do or journal. For a given pair of "UID" and 5003 "SEQUENCE" property values, the "RECURRENCE-ID" value for a 5004 recurrence instance is fixed. When the definition of the 5005 recurrence set for a calendar component changes, and hence the 5006 "SEQUENCE" property value changes, the "RECURRENCE-ID" for a given 5007 recurrence instance might also change.The "RANGE" parameter is 5008 used to specify the effective range of recurrence instances from 5009 the instance specified by the "RECURRENCE-ID" property value. The 5010 default value for the range parameter is the single recurrence 5011 instance only. The value can also be "THISANDPRIOR" to indicate a 5012 range defined by the given recurrence instance and all prior 5013 instances or the value can be "THISANDFUTURE" to indicate a range 5014 defined by the given recurrence instance and all subsequent 5015 instances. 5017 Format Definition: The property is defined by the following notation: 5019 recurid = "RECURRENCE-ID" ridparam ":" ridval CRLF 5021 ridparam = *( 5023 ; the following are optional, 5024 ; but MUST NOT occur more than once 5026 (";" "VALUE" "=" ("DATE-TIME" / "DATE)) / 5027 (";" tzidparam) / (";" rangeparam) / 5029 ; the following is optional, 5030 ; and MAY occur more than once 5032 (";" xparam) 5034 ) 5036 ridval = date-time / date 5037 ;Value MUST match value type 5039 Example: The following are examples of this property: 5041 RECURRENCE-ID;VALUE=DATE:19960401 5043 RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z 5045 3.8.4.5. Related To 5047 Property Name: RELATED-TO 5049 Purpose: The property is used to represent a relationship or 5050 reference between one calendar component and another. 5052 Value Type: TEXT 5054 Property Parameters: Non-standard and relationship type property 5055 parameters can be specified on this property. 5057 Conformance: The property can be specified one or more times in the 5058 "VEVENT", "VTODO" or "VJOURNAL" calendar components. 5060 Description: The property value consists of the persistent, globally 5061 unique identifier of another calendar component. This value would 5062 be represented in a calendar component by the "UID" property. 5064 By default, the property value points to another calendar 5065 component that has a PARENT relationship to the referencing 5066 object. The "RELTYPE" property parameter is used to either 5067 explicitly state the default PARENT relationship type to the 5068 referenced calendar component or to override the default PARENT 5069 relationship type and specify either a CHILD or SIBLING 5070 relationship. The PARENT relationship indicates that the calendar 5071 component is a subordinate of the referenced calendar component. 5072 The CHILD relationship indicates that the calendar component is a 5073 superior of the referenced calendar component. The SIBLING 5074 relationship indicates that the calendar component is a peer of 5075 the referenced calendar component. 5077 Changes to a calendar component referenced by this property can 5078 have an implicit impact on the related calendar component. For 5079 example, if a group event changes its start or end date or time, 5080 then the related, dependent events will need to have their start 5081 and end dates changed in a corresponding way. Similarly, if a 5082 PARENT calendar component is cancelled or deleted, then there is 5083 an implied impact to the related CHILD calendar components. This 5084 property is intended only to provide information on the 5085 relationship of calendar components. It is up to the target 5086 calendar system to maintain any property implications of this 5087 relationship. 5089 Format Definition: The property is defined by the following notation: 5091 related = "RELATED-TO" relparam ":" text CRLF 5093 relparam = *( 5095 ; the following is optional, 5096 ; but MUST NOT occur more than once 5098 (";" reltypeparam) / 5100 ; the following is optional, 5101 ; and MAY occur more than once 5103 (";" xparam) 5105 ) 5107 The following is an example of this property: 5109 RELATED-TO:jsmith.part7.19960817T083000.xyzMail@example.com 5110 RELATED-TO:19960401-080045-4000F192713-0052@example.com 5112 3.8.4.6. Uniform Resource Locator 5114 Property Name: URL 5116 Purpose: This property defines a Uniform Resource Locator (URL) 5117 associated with the iCalendar object. 5119 Value Type: URI 5121 Property Parameters: Non-standard property parameters can be 5122 specified on this property. 5124 Conformance: This property can be specified once in the "VEVENT", 5125 "VTODO", "VJOURNAL" or "VFREEBUSY" calendar components. 5127 Description: This property may be used in a calendar component to 5128 convey a location where a more dynamic rendition of the calendar 5129 information associated with the calendar component can be found. 5130 This memo does not attempt to standardize the form of the URI, nor 5131 the format of the resource pointed to by the property value. If 5132 the URL property and Content-Location MIME header are both 5133 specified, they MUST point to the same resource. 5135 Format Definition: The property is defined by the following notation: 5137 url = "URL" urlparam ":" uri CRLF 5139 urlparam = *(";" xparam) 5141 Example: The following is an example of this property: 5143 URL:http://abc.com/pub/calendars/jsmith/mytime.ics 5145 3.8.4.7. Unique Identifier 5147 Property Name: UID 5149 Purpose: This property defines the persistent, globally unique 5150 identifier for the calendar component. 5152 Value Type: TEXT 5154 Property Parameters: Non-standard property parameters can be 5155 specified on this property. 5157 Conformance: The property MUST be specified in the "VEVENT", "VTODO", 5158 "VJOURNAL" or "VFREEBUSY" calendar components. 5160 Description: The UID itself MUST be a globally unique identifier. 5161 The generator of the identifier MUST guarantee that the identifier 5162 is unique. There are several algorithms that can be used to 5163 accomplish this. The identifier is RECOMMENDED to be the 5164 identical syntax to the [RFC2822] addr-spec. A good method to 5165 assure uniqueness is to put the domain name or a domain literal IP 5166 address of the host on which the identifier was created on the 5167 right hand side of the "@", and on the left hand side, put a 5168 combination of the current calendar date and time of day (i.e., 5169 formatted in as a DATE-TIME value) along with some other currently 5170 unique (perhaps sequential) identifier available on the system 5171 (for example, a process id number). Using a date/time value on 5172 the left hand side and a domain name or domain literal on the 5173 right hand side makes it possible to guarantee uniqueness since no 5174 two hosts should be using the same domain name or IP address at 5175 the same time. Though other algorithms will work, it is 5176 RECOMMENDED that the right hand side contain some domain 5177 identifier (either of the host itself or otherwise) such that the 5178 generator of the message identifier can guarantee the uniqueness 5179 of the left hand side within the scope of that domain. 5181 This is the method for correlating scheduling messages with the 5182 referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component. 5184 The full range of calendar components specified by a recurrence 5185 set is referenced by referring to just the "UID" property value 5186 corresponding to the calendar component. The "RECURRENCE-ID" 5187 property allows the reference to an individual instance within the 5188 recurrence set. 5190 This property is an important method for group scheduling 5191 applications to match requests with later replies, modifications 5192 or deletion requests. Calendaring and scheduling applications 5193 MUST generate this property in "VEVENT", "VTODO" and "VJOURNAL" 5194 calendar components to assure interoperability with other group 5195 scheduling applications. This identifier is created by the 5196 calendar system that generates an iCalendar object. 5198 Implementations MUST be able to receive and persist values of at 5199 least 255 octets for this property but MUST NOT truncate values in 5200 the middle of a UTF-8 multi-octet sequence . 5202 Format Definition: The property is defined by the following notation: 5204 uid = "UID" uidparam ":" text CRLF 5206 uidparam = *(";" xparam) 5208 Example: The following is an example of this property: 5210 UID:19960401T080045Z-4000F192713-0052@example.com 5212 3.8.5. Recurrence Component Properties 5214 The following properties specify recurrence information in calendar 5215 components. 5217 3.8.5.1. Exception Date/Times 5219 Property Name: EXDATE 5221 Purpose: This property defines the list of date/time exceptions for a 5222 recurring calendar component. 5224 Value Type: The default value type for this property is DATE-TIME. 5225 The value type can be set to DATE. 5227 Property Parameters: Non-standard, value data type and time zone 5228 identifier property parameters can be specified on this property. 5230 Conformance: This property can be specified in an iCalendar object 5231 that includes a recurring calendar component. 5233 Description: The exception dates, if specified, are used in computing 5234 the recurrence set. The recurrence set is the complete set of 5235 recurrence instances for a calendar component. The recurrence set 5236 is generated by considering the initial "DTSTART" property along 5237 with the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties 5238 contained within the iCalendar object. The "DTSTART" property 5239 defines the first instance in the recurrence set. Multiple 5240 instances of the "RRULE" and "EXRULE" properties can also be 5241 specified to define more sophisticated recurrence sets. The final 5242 recurrence set is generated by gathering all of the start date- 5243 times generated by any of the specified "RRULE" and "RDATE" 5244 properties, and then excluding any start date and times which fall 5245 within the union of start date and times generated by any 5246 specified "EXRULE" and "EXDATE" properties. This implies that 5247 start date and times within exclusion related properties (i.e., 5248 "EXDATE" and "EXRULE") take precedence over those specified by 5249 inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate 5250 instances are generated by the "RRULE" and "RDATE" properties, 5251 only one recurrence is considered. Duplicate instances are 5252 ignored. 5254 The "EXDATE" property can be used to exclude the value specified 5255 in "DTSTART". However, in such cases the original "DTSTART" date 5256 MUST still be maintained by the calendaring and scheduling system 5257 because the original "DTSTART" value has inherent usage 5258 dependencies by other properties such as the "RECURRENCE-ID". 5260 Format Definition: The property is defined by the following notation: 5262 exdate = "EXDATE" exdtparam ":" exdtval *("," exdtval) CRLF 5264 exdtparam = *( 5266 ; the following are optional, 5267 ; but MUST NOT occur more than once 5269 (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / 5271 (";" tzidparam) / 5273 ; the following is optional, 5274 ; and MAY occur more than once 5276 (";" xparam) 5278 ) 5280 exdtval = date-time / date 5281 ;Value MUST match value type 5283 Example: The following is an example of this property: 5285 EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z 5287 3.8.5.2. Exception Rule 5289 Property Name: EXRULE 5291 Purpose: This property defines a rule or repeating pattern for an 5292 exception to a recurrence set. 5294 Value Type: RECUR 5295 Property Parameters: Non-standard property parameters can be 5296 specified on this property. 5298 Conformance: This property can be specified in "VEVENT", "VTODO" or 5299 "VJOURNAL" calendar components. 5301 Description: The exception rule, if specified, is used in computing 5302 the recurrence set. The recurrence set is the complete set of 5303 recurrence instances for a calendar component. The recurrence set 5304 is generated by considering the initial "DTSTART" property along 5305 with the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties 5306 contained within the iCalendar object. The "DTSTART" defines the 5307 first instance in the recurrence set. Multiple instances of the 5308 "RRULE" and "EXRULE" properties can also be specified to define 5309 more sophisticated recurrence sets. The final recurrence set is 5310 generated by gathering all of the start date-times generated by 5311 any of the specified "RRULE" and "RDATE" properties, and excluding 5312 any start date and times which fall within the union of start date 5313 and times generated by any specified "EXRULE" and "EXDATE" 5314 properties. This implies that start date and times within 5315 exclusion related properties (i.e., "EXDATE" and "EXRULE") take 5316 precedence over those specified by inclusion properties (i.e., 5317 "RDATE" and "RRULE"). Where duplicate instances are generated by 5318 the "RRULE" and "RDATE" properties, only one recurrence is 5319 considered. Duplicate instances are ignored. 5321 The "EXRULE" property can be used to exclude the value specified 5322 in "DTSTART". However, in such cases the original "DTSTART" date 5323 MUST still be maintained by the calendaring and scheduling system 5324 because the original "DTSTART" value has inherent usage 5325 dependencies by other properties such as the "RECURRENCE-ID". 5327 Format Definition: The property is defined by the following notation: 5329 exrule = "EXRULE" exrparam ":" recur CRLF 5331 exrparam = *(";" xparam) 5333 Example: The following are examples of this property. Except every 5334 other week, on Tuesday and Thursday for 4 occurrences: 5336 EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH 5338 Except daily for 10 occurrences: 5340 EXRULE:FREQ=DAILY;COUNT=10 5342 Except yearly in June and July for 8 occurrences: 5344 EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7 5346 3.8.5.3. Recurrence Date/Times 5348 Property Name: RDATE 5350 Purpose: This property defines the list of date/times for a 5351 recurrence set. 5353 Value Type: The default value type for this property is DATE-TIME. 5354 The value type can be set to DATE or PERIOD. 5356 Property Parameters: Non-standard, value data type and time zone 5357 identifier property parameters can be specified on this property. 5359 Conformance: The property can be specified in "VEVENT", "VTODO", 5360 "VJOURNAL" or "VTIMEZONE" calendar components. 5362 Description: This property can appear along with the "RRULE" property 5363 to define an aggregate set of repeating occurrences. When they 5364 both appear in an iCalendar object, the recurring events are 5365 defined by the union of occurrences defined by both the "RDATE" 5366 and "RRULE". 5368 The recurrence dates, if specified, are used in computing the 5369 recurrence set. The recurrence set is the complete set of 5370 recurrence instances for a calendar component. The recurrence set 5371 is generated by considering the initial "DTSTART" property along 5372 with the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties 5373 contained within the iCalendar object. The "DTSTART" property 5374 defines the first instance in the recurrence set. Multiple 5375 instances of the "RRULE" and "EXRULE" properties can also be 5376 specified to define more sophisticated recurrence sets. The final 5377 recurrence set is generated by gathering all of the start date/ 5378 times generated by any of the specified "RRULE" and "RDATE" 5379 properties, and excluding any start date/times which fall within 5380 the union of start date/times generated by any specified "EXRULE" 5381 and "EXDATE" properties. This implies that start date/times 5382 within exclusion related properties (i.e., "EXDATE" and "EXRULE") 5383 take precedence over those specified by inclusion properties 5384 (i.e., "RDATE" and "RRULE"). Where duplicate instances are 5385 generated by the "RRULE" and "RDATE" properties, only one 5386 recurrence is considered. Duplicate instances are ignored. 5388 Format Definition: The property is defined by the following notation: 5390 rdate = "RDATE" rdtparam ":" rdtval *("," rdtval) CRLF 5392 rdtparam = *( 5394 ; the following are optional, 5395 ; but MUST NOT occur more than once 5397 (";" "VALUE" "=" ("DATE-TIME" / "DATE" / "PERIOD")) / 5398 (";" tzidparam) / 5400 ; the following is optional, 5401 ; and MAY occur more than once 5403 (";" xparam) 5405 ) 5407 rdtval = date-time / date / period 5408 ;Value MUST match value type 5410 Example: The following are examples of this property: 5412 RDATE:19970714T123000Z 5414 RDATE;TZID=US-EASTERN:19970714T083000 5416 RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z, 5417 19960404T010000Z/PT3H 5419 RDATE;VALUE=DATE:19970101,19970120,19970217,19970421 5420 19970526,19970704,19970901,19971014,19971128,19971129,19971225 5422 3.8.5.4. Recurrence Rule 5424 Property Name: RRULE 5426 Purpose: This property defines a rule or repeating pattern for 5427 recurring events, to-dos, or time zone definitions. 5429 Value Type: RECUR 5431 Property Parameters: Non-standard property parameters can be 5432 specified on this property. 5434 Conformance: This property can be specified one or more times in 5435 recurring "VEVENT", "VTODO" and "VJOURNAL" calendar components. 5436 It can also be specified once in each STANDARD or DAYLIGHT sub- 5437 component of the "VTIMEZONE" calendar component. 5439 Description: The recurrence rule, if specified, is used in computing 5440 the recurrence set. The recurrence set is the complete set of 5441 recurrence instances for a calendar component. The recurrence set 5442 is generated by considering the initial "DTSTART" property along 5443 with the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties 5444 contained within the iCalendar object. The "DTSTART" property 5445 defines the first instance in the recurrence set. Multiple 5446 instances of the "RRULE" and "EXRULE" properties can also be 5447 specified to define more sophisticated recurrence sets. The final 5448 recurrence set is generated by gathering all of the start date/ 5449 times generated by any of the specified "RRULE" and "RDATE" 5450 properties, and excluding any start date/times which fall within 5451 the union of start date/times generated by any specified "EXRULE" 5452 and "EXDATE" properties. This implies that start date/times 5453 within exclusion related properties (i.e., "EXDATE" and "EXRULE") 5454 take precedence over those specified by inclusion properties 5455 (i.e., "RDATE" and "RRULE"). Where duplicate instances are 5456 generated by the "RRULE" and "RDATE" properties, only one 5457 recurrence is considered. Duplicate instances are ignored. 5459 The "DTSTART" and "DTEND" property pair or "DTSTART" and 5460 "DURATION" property pair, specified within the iCalendar object 5461 defines the first instance of the recurrence. When used with a 5462 recurrence rule, the "DTSTART" and "DTEND" properties MUST be 5463 specified in local time and the appropriate set of "VTIMEZONE" 5464 calendar components MUST be included. For detail on the usage of 5465 the "VTIMEZONE" calendar component, see the "VTIMEZONE" calendar 5466 component definition. 5468 Any duration associated with the iCalendar object applies to all 5469 members of the generated recurrence set. Any modified duration 5470 for specific recurrences MUST be explicitly specified using the 5471 "RDATE" property. 5473 Format Definition: The property is defined by the following notation: 5475 rrule = "RRULE" rrulparam ":" recur CRLF 5477 rrulparam = *(";" xparam) 5479 Example: All examples assume the Eastern United States time zone. 5481 Daily for 10 occurrences: 5483 DTSTART;TZID=US-Eastern:19970902T090000 5484 RRULE:FREQ=DAILY;COUNT=10 5486 ==> (1997 9:00 AM EDT)September 2-11 5488 Daily until December 24, 1997: 5490 DTSTART;TZID=US-Eastern:19970902T090000 5491 RRULE:FREQ=DAILY;UNTIL=19971224T000000Z 5493 ==> (1997 9:00 AM EDT)September 2-30;October 1-25 5494 (1997 9:00 AM EST)October 26-31;November 1-30;December 1-23 5496 Every other day - forever: 5498 DTSTART;TZID=US-Eastern:19970902T090000 5499 RRULE:FREQ=DAILY;INTERVAL=2 5501 ==> (1997 9:00 AM EDT)September 2,4,6,8...24,26,28,30; 5502 October 2,4,6...20,22,24 5503 (1997 9:00 AM EST)October 26,28,30;November 1,3,5,7...25,27,29; 5504 December 1,3,... 5506 Every 10 days, 5 occurrences: 5508 DTSTART;TZID=US-Eastern:19970902T090000 5509 RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5 5511 ==> (1997 9:00 AM EDT)September 2,12,22;October 2,12 5513 Everyday in January, for 3 years: 5515 DTSTART;TZID=US-Eastern:19980101T090000 5517 RRULE:FREQ=YEARLY;UNTIL=20000131T140000Z; 5518 BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA 5519 or 5520 RRULE:FREQ=DAILY;UNTIL=20000131T140000Z;BYMONTH=1 5522 ==> (1998 9:00 AM EST)January 1-31 5523 (1999 9:00 AM EST)January 1-31 5524 (2000 9:00 AM EST)January 1-31 5526 Weekly for 10 occurrences 5528 DTSTART;TZID=US-Eastern:19970902T090000 5529 RRULE:FREQ=WEEKLY;COUNT=10 5531 ==> (1997 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21 5532 (1997 9:00 AM EST)October 28;November 4 5534 Weekly until December 24, 1997 5536 DTSTART;TZID=US-Eastern:19970902T090000 5537 RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z 5539 ==> (1997 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21 5540 (1997 9:00 AM EST)October 28;November 4,11,18,25; 5541 December 2,9,16,23 5543 Every other week - forever: 5545 DTSTART;TZID=US-Eastern:19970902T090000 5546 RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU 5548 ==> (1997 9:00 AM EDT)September 2,16,30;October 14 5549 (1997 9:00 AM EST)October 28;November 11,25;December 9,23 5550 (1998 9:00 AM EST)January 6,20;February 5551 ... 5553 Weekly on Tuesday and Thursday for 5 weeks: 5555 DTSTART;TZID=US-Eastern:19970902T090000 5556 RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;WKST=SU;BYDAY=TU,TH 5557 or 5559 RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH 5561 ==> (1997 9:00 AM EDT)September 2,4,9,11,16,18,23,25,30;October 2 5563 Every other week on Monday, Wednesday and Friday until December 5564 24, 1997, but starting on Tuesday, September 2, 1997: 5566 DTSTART;TZID=US-Eastern:19970902T090000 5567 RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;WKST=SU; 5568 BYDAY=MO,WE,FR 5570 ==> (1997 9:00 AM EDT)September 2,3,5,15,17,19,29;October 5571 1,3,13,15,17 5572 (1997 9:00 AM EST)October 27,29,31;November 10,12,14,24,26,28; 5573 December 8,10,12,22 5575 Every other week on Tuesday and Thursday, for 8 occurrences: 5577 DTSTART;TZID=US-Eastern:19970902T090000 5578 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH 5580 ==> (1997 9:00 AM EDT)September 2,4,16,18,30;October 2,14,16 5582 Monthly on the 1st Friday for ten occurrences: 5584 DTSTART;TZID=US-Eastern:19970905T090000 5585 RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR 5587 ==> (1997 9:00 AM EDT)September 5;October 3 5588 (1997 9:00 AM EST)November 7;December 5 5589 (1998 9:00 AM EST)January 2;February 6;March 6;April 3 5590 (1998 9:00 AM EDT)May 1;June 5 5592 Monthly on the 1st Friday until December 24, 1997: 5594 DTSTART;TZID=US-Eastern:19970905T090000 5595 RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR 5597 ==> (1997 9:00 AM EDT)September 5;October 3 5598 (1997 9:00 AM EST)November 7;December 5 5600 Every other month on the 1st and last Sunday of the month for 10 5601 occurrences: 5603 DTSTART;TZID=US-Eastern:19970907T090000 5604 RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU 5606 ==> (1997 9:00 AM EDT)September 7,28 5607 (1997 9:00 AM EST)November 2,30 5608 (1998 9:00 AM EST)January 4,25;March 1,29 5609 (1998 9:00 AM EDT)May 3,31 5611 Monthly on the second to last Monday of the month for 6 months: 5613 DTSTART;TZID=US-Eastern:19970922T090000 5614 RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO 5616 ==> (1997 9:00 AM EDT)September 22;October 20 5617 (1997 9:00 AM EST)November 17;December 22 5618 (1998 9:00 AM EST)January 19;February 16 5620 Monthly on the third to the last day of the month, forever: 5622 DTSTART;TZID=US-Eastern:19970928T090000 5623 RRULE:FREQ=MONTHLY;BYMONTHDAY=-3 5625 ==> (1997 9:00 AM EDT)September 28 5626 (1997 9:00 AM EST)October 29;November 28;December 29 5627 (1998 9:00 AM EST)January 29;February 26 5628 ... 5630 Monthly on the 2nd and 15th of the month for 10 occurrences: 5632 DTSTART;TZID=US-Eastern:19970902T090000 5633 RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15 5635 ==> (1997 9:00 AM EDT)September 2,15;October 2,15 5636 (1997 9:00 AM EST)November 2,15;December 2,15 5637 (1998 9:00 AM EST)January 2,15 5639 Monthly on the first and last day of the month for 10 occurrences: 5641 DTSTART;TZID=US-Eastern:19970930T090000 5642 RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1 5644 ==> (1997 9:00 AM EDT)September 30;October 1 5645 (1997 9:00 AM EST)October 31;November 1,30;December 1,31 5646 (1998 9:00 AM EST)January 1,31;February 1 5648 Every 18 months on the 10th thru 15th of the month for 10 5649 occurrences: 5651 DTSTART;TZID=US-Eastern:19970910T090000 5652 RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14, 5653 15 5655 ==> (1997 9:00 AM EDT)September 10,11,12,13,14,15 5656 (1999 9:00 AM EST)March 10,11,12,13 5658 Every Tuesday, every other month: 5660 DTSTART;TZID=US-Eastern:19970902T090000 5661 RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU 5663 ==> (1997 9:00 AM EDT)September 2,9,16,23,30 5664 (1997 9:00 AM EST)November 4,11,18,25 5665 (1998 9:00 AM EST)January 6,13,20,27;March 3,10,17,24,31 5666 ... 5668 Yearly in June and July for 10 occurrences: 5670 DTSTART;TZID=US-Eastern:19970610T090000 5671 RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7 5672 ==> (1997 9:00 AM EDT)June 10;July 10 5673 (1998 9:00 AM EDT)June 10;July 10 5674 (1999 9:00 AM EDT)June 10;July 10 5675 (2000 9:00 AM EDT)June 10;July 10 5676 (2001 9:00 AM EDT)June 10;July 10 5677 Note: Since none of the BYDAY, BYMONTHDAY or BYYEARDAY components 5678 are specified, the day is gotten from DTSTART 5680 Every other year on January, February, and March for 10 5681 occurrences: 5683 DTSTART;TZID=US-Eastern:19970310T090000 5684 RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3 5686 ==> (1997 9:00 AM EST)March 10 5687 (1999 9:00 AM EST)January 10;February 10;March 10 5688 (2001 9:00 AM EST)January 10;February 10;March 10 5689 (2003 9:00 AM EST)January 10;February 10;March 10 5691 Every 3rd year on the 1st, 100th and 200th day for 10 occurrences: 5693 DTSTART;TZID=US-Eastern:19970101T090000 5694 RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200 5696 ==> (1997 9:00 AM EST)January 1 5697 (1997 9:00 AM EDT)April 10;July 19 5698 (2000 9:00 AM EST)January 1 5699 (2000 9:00 AM EDT)April 9;July 18 5700 (2003 9:00 AM EST)January 1 5701 (2003 9:00 AM EDT)April 10;July 19 5702 (2006 9:00 AM EST)January 1 5704 Every 20th Monday of the year, forever: 5706 DTSTART;TZID=US-Eastern:19970519T090000 5707 RRULE:FREQ=YEARLY;BYDAY=20MO 5709 ==> (1997 9:00 AM EDT)May 19 5710 (1998 9:00 AM EDT)May 18 5711 (1999 9:00 AM EDT)May 17 5712 ... 5714 Monday of week number 20 (where the default start of the week is 5715 Monday), forever: 5717 DTSTART;TZID=US-Eastern:19970512T090000 5718 RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO 5720 ==> (1997 9:00 AM EDT)May 12 5721 (1998 9:00 AM EDT)May 11 5722 (1999 9:00 AM EDT)May 17 5723 ... 5725 Every Thursday in March, forever: 5727 DTSTART;TZID=US-Eastern:19970313T090000 5728 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH 5730 ==> (1997 9:00 AM EST)March 13,20,27 5731 (1998 9:00 AM EST)March 5,12,19,26 5732 (1999 9:00 AM EST)March 4,11,18,25 5733 ... 5735 Every Thursday, but only during June, July, and August, forever: 5737 DTSTART;TZID=US-Eastern:19970605T090000 5738 RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8 5740 ==> (1997 9:00 AM EDT)June 5,12,19,26;July 3,10,17,24,31; 5741 August 7,14,21,28 5742 (1998 9:00 AM EDT)June 4,11,18,25;July 2,9,16,23,30; 5743 August 6,13,20,27 5744 (1999 9:00 AM EDT)June 3,10,17,24;July 1,8,15,22,29; 5745 August 5,12,19,26 5746 ... 5748 Every Friday the 13th, forever: 5750 DTSTART;TZID=US-Eastern:19970902T090000 5751 EXDATE;TZID=US-Eastern:19970902T090000 5752 RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13 5754 ==> (1998 9:00 AM EST)February 13;March 13;November 13 5755 (1999 9:00 AM EDT)August 13 5756 (2000 9:00 AM EDT)October 13 5757 ... 5759 The first Saturday that follows the first Sunday of the month, 5760 forever: 5762 DTSTART;TZID=US-Eastern:19970913T090000 5763 RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13 5765 ==> (1997 9:00 AM EDT)September 13;October 11 5766 (1997 9:00 AM EST)November 8;December 13 5767 (1998 9:00 AM EST)January 10;February 7;March 7 5768 (1998 9:00 AM EDT)April 11;May 9;June 13... 5769 ... 5771 Every four years, the first Tuesday after a Monday in November, 5772 forever (U.S. Presidential Election day): 5774 DTSTART;TZID=US-Eastern:19961105T090000 5775 RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4, 5776 5,6,7,8 5778 ==> (1996 9:00 AM EST)November 5 5779 (2000 9:00 AM EST)November 7 5780 (2004 9:00 AM EST)November 2 5781 ... 5783 The 3rd instance into the month of one of Tuesday, Wednesday or 5784 Thursday, for the next 3 months: 5786 DTSTART;TZID=US-Eastern:19970904T090000 5787 RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3 5789 ==> (1997 9:00 AM EDT)September 4;October 7 5790 (1997 9:00 AM EST)November 6 5792 The 2nd to last weekday of the month: 5794 DTSTART;TZID=US-Eastern:19970929T090000 5795 RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2 5797 ==> (1997 9:00 AM EDT)September 29 5798 (1997 9:00 AM EST)October 30;November 27;December 30 5799 (1998 9:00 AM EST)January 29;February 26;March 30 5800 ... 5802 Every 3 hours from 9:00 AM to 5:00 PM on a specific day: 5804 DTSTART;TZID=US-Eastern:19970902T090000 5805 RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000Z 5806 ==> (September 2, 1997 EDT)09:00,12:00,15:00 5808 Every 15 minutes for 6 occurrences: 5810 DTSTART;TZID=US-Eastern:19970902T090000 5811 RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6 5813 ==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15 5815 Every hour and a half for 4 occurrences: 5817 DTSTART;TZID=US-Eastern:19970902T090000 5818 RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4 5820 ==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30 5822 Every 20 minutes from 9:00 AM to 4:40 PM every day: 5824 DTSTART;TZID=US-Eastern:19970902T090000 5825 RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40 5826 or 5827 RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16 5829 ==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20, 5830 ... 16:00,16:20,16:40 5831 (September 3, 1997 EDT)9:00,9:20,9:40,10:00,10:20, 5832 ...16:00,16:20,16:40 5833 ... 5835 An example where the days generated makes a difference because of 5836 WKST: 5838 DTSTART;TZID=US-Eastern:19970805T090000 5839 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO 5841 ==> (1997 EDT)Aug 5,10,19,24 5843 changing only WKST from MO to SU, yields different results... 5845 DTSTART;TZID=US-Eastern:19970805T090000 5846 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU 5847 ==> (1997 EDT)August 5,17,19,31 5849 3.8.6. Alarm Component Properties 5851 The following properties specify alarm information in calendar 5852 components. 5854 3.8.6.1. Action 5856 Property Name: ACTION 5858 Purpose: This property defines the action to be invoked when an alarm 5859 is triggered. 5861 Value Type: TEXT 5863 Property Parameters: Non-standard property parameters can be 5864 specified on this property. 5866 Conformance: This property MUST be specified once in a "VALARM" 5867 calendar component. 5869 Description: Each "VALARM" calendar component has a particular type 5870 of action associated with it. This property specifies the type of 5871 action 5873 Format Definition: The property is defined by the following notation: 5875 action = "ACTION" actionparam ":" actionvalue CRLF 5877 actionparam = *(";" xparam) 5879 actionvalue = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE" 5880 / iana-token / x-name 5882 Example: The following are examples of this property in a "VALARM" 5883 calendar component: 5885 ACTION:AUDIO 5887 ACTION:DISPLAY 5889 ACTION:PROCEDURE 5891 3.8.6.2. Repeat Count 5893 Property Name: REPEAT 5895 Purpose: This property defines the number of time the alarm should be 5896 repeated, after the initial trigger. 5898 Value Type: INTEGER 5899 Property Parameters: Non-standard property parameters can be 5900 specified on this property. 5902 Conformance: This property can be specified in a "VALARM" calendar 5903 component. 5905 Description: If the alarm triggers more than once, then this property 5906 MUST be specified along with the "DURATION" property. 5908 Format Definition: The property is defined by the following notation: 5910 repeatcnt = "REPEAT" repparam ":" integer CRLF 5911 ;Default is "0", zero. 5913 repparam = *(";" xparam) 5915 Example: The following is an example of this property for an alarm 5916 that repeats 4 additional times with a 5 minute delay after the 5917 initial triggering of the alarm: 5919 REPEAT:4 5920 DURATION:PT5M 5922 3.8.6.3. Trigger 5924 Property Name: TRIGGER 5926 Purpose: This property specifies when an alarm will trigger. 5928 Value Type: The default value type is DURATION. The value type can 5929 be set to a DATE-TIME value type, in which case the value MUST 5930 specify a UTC formatted DATE-TIME value. 5932 Property Parameters: Non-standard, value data type, time zone 5933 identifier or trigger relationship property parameters can be 5934 specified on this property. The trigger relationship property 5935 parameter MUST only be specified when the value type is DURATION. 5937 Conformance: This property MUST be specified in the "VALARM" calendar 5938 component. 5940 Description: Within the "VALARM" calendar component, this property 5941 defines when the alarm will trigger. The default value type is 5942 DURATION, specifying a relative time for the trigger of the alarm. 5943 The default duration is relative to the start of an event or to-do 5944 that the alarm is associated with. The duration can be explicitly 5945 set to trigger from either the end or the start of the associated 5946 event or to-do with the "RELATED" parameter. A value of START 5947 will set the alarm to trigger off the start of the associated 5948 event or to-do. A value of END will set the alarm to trigger off 5949 the end of the associated event or to-do. 5951 Either a positive or negative duration may be specified for the 5952 "TRIGGER" property. An alarm with a positive duration is 5953 triggered after the associated start or end of the event or to-do. 5954 An alarm with a negative duration is triggered before the 5955 associated start or end of the event or to-do. 5957 The "RELATED" property parameter is not valid if the value type of 5958 the property is set to DATE-TIME (i.e., for an absolute date and 5959 time alarm trigger). If a value type of DATE-TIME is specified, 5960 then the property value MUST be specified in the UTC time format. 5961 If an absolute trigger is specified on an alarm for a recurring 5962 event or to-do, then the alarm will only trigger for the specified 5963 absolute date/time, along with any specified repeating instances. 5965 If the trigger is set relative to START, then the "DTSTART" 5966 property MUST be present in the associated "VEVENT" or "VTODO" 5967 calendar component. If an alarm is specified for an event with 5968 the trigger set relative to the END, then the "DTEND" property or 5969 the "DTSTART" and "DURATION " properties MUST be present in the 5970 associated "VEVENT" calendar component. If the alarm is specified 5971 for a to-do with a trigger set relative to the END, then either 5972 the "DUE" property or the "DTSTART" and "DURATION " properties 5973 MUST be present in the associated "VTODO" calendar component. 5975 Alarms specified in an event or to-do which is defined in terms of 5976 a DATE value type will be triggered relative to 00:00:00 UTC on 5977 the specified date. For example, if DTSTART is a DATE value set 5978 to 19980205 then the duration trigger will be relative to 5979 19980205T000000Z. 5981 Format Definition: The property is defined by the following notation: 5983 trigger = "TRIGGER" (trigrel / trigabs) CRLF 5985 trigrel = *( 5987 ; the following are optional, 5988 ; but MUST NOT occur more than once 5990 (";" "VALUE" "=" "DURATION") / 5991 (";" trigrelparam) / 5993 ; the following is optional, 5994 ; and MAY occur more than once 5996 (";" xparam) 5997 ) ":" dur-value 5999 trigabs = 1*( 6001 ; the following is REQUIRED, 6002 ; but MUST NOT occur more than once 6004 (";" "VALUE" "=" "DATE-TIME") / 6006 ; the following is optional, 6007 ; and MAY occur more than once 6009 (";" xparam) 6011 ) ":" date-time 6013 Example: A trigger set 15 minutes prior to the start of the event or 6014 to-do. 6016 TRIGGER:-P15M 6018 A trigger set 5 minutes after the end of the event or to-do. 6020 TRIGGER;RELATED=END:P5M 6022 A trigger set to an absolute date/time. 6024 TRIGGER;VALUE=DATE-TIME:19980101T050000Z 6026 3.8.7. Change Management Component Properties 6028 The following properties specify change management information in 6029 calendar components. 6031 3.8.7.1. Date/Time Created 6033 Property Name: CREATED 6035 Purpose: This property specifies the date and time that the calendar 6036 information was created by the calendar user agent in the calendar 6037 store. 6039 Note: This is analogous to the creation date and time for a 6040 file in the file system. 6042 Value Type: DATE-TIME 6044 Property Parameters: Non-standard property parameters can be 6045 specified on this property. 6047 Conformance: The property can be specified once in "VEVENT", "VTODO" 6048 or "VJOURNAL" calendar components. 6050 Description: The date and time is a UTC value. 6052 Format Definition: The property is defined by the following notation: 6054 created = "CREATED" creaparam ":" date-time CRLF 6056 creaparam = *(";" xparam) 6058 Example: The following is an example of this property: 6060 CREATED:19960329T133000Z 6062 3.8.7.2. Date/Time Stamp 6064 Property Name: DTSTAMP 6066 Purpose: The property indicates the date/time that the instance of 6067 the iCalendar object was created. 6069 Value Type: DATE-TIME 6071 Property Parameters: Non-standard property parameters can be 6072 specified on this property. 6074 Conformance: This property MUST be included in the "VEVENT", "VTODO", 6075 "VJOURNAL" or "VFREEBUSY" calendar components. 6077 Description: The value MUST be specified in the UTC time format. 6079 This property is also useful to protocols such as [I-D.ietf- 6080 calsify-rfc2447bis] that have inherent latency issues with the 6081 delivery of content. This property will assist in the proper 6082 sequencing of messages containing iCalendar objects. 6084 This property is different than the "CREATED" and "LAST-MODIFIED" 6085 properties. These two properties are used to specify when the 6086 particular calendar data in the calendar store was created and 6087 last modified. This is different than when the iCalendar object 6088 representation of the calendar service information was created or 6089 last modified. 6091 Format Definition: The property is defined by the following notation: 6093 dtstamp = "DTSTAMP" stmparam ":" date-time CRLF 6095 stmparam = *(";" xparam) 6097 Example: 6099 DTSTAMP:19971210T080000Z 6101 3.8.7.3. Last Modified 6103 Property Name: LAST-MODIFIED 6105 Purpose: The property specifies the date and time that the 6106 information associated with the calendar component was last 6107 revised in the calendar store. 6109 Note: This is analogous to the modification date and time for a 6110 file in the file system. 6112 Value Type: DATE-TIME 6114 Property Parameters: Non-standard property parameters can be 6115 specified on this property. 6117 Conformance: This property can be specified in the "EVENT", "VTODO", 6118 "VJOURNAL" or "VTIMEZONE" calendar components. 6120 Description: The property value MUST be specified in the UTC time 6121 format. 6123 Format Definition: The property is defined by the following notation: 6125 last-mod = "LAST-MODIFIED" lstparam ":" date-time CRLF 6127 lstparam = *(";" xparam) 6129 Example: The following are examples of this property: 6131 LAST-MODIFIED:19960817T133000Z 6133 3.8.7.4. Sequence Number 6135 Property Name: SEQUENCE 6137 Purpose: This property defines the revision sequence number of the 6138 calendar component within a sequence of revisions. 6140 Value Type: INTEGER 6142 Property Parameters: Non-standard property parameters can be 6143 specified on this property. 6145 Conformance: The property can be specified in "VEVENT", "VTODO" or 6146 "VJOURNAL" calendar component. 6148 Description: When a calendar component is created, its sequence 6149 number is zero (US-ASCII decimal 48). It is monotonically 6150 incremented by the "Organizer's" CUA each time the "Organizer" 6151 makes a significant revision to the calendar component. When the 6152 "Organizer" makes changes to one of the following properties, the 6153 sequence number MUST be incremented: 6155 * "DTSTART" 6157 * "DTEND" 6159 * "DURATION" 6161 * "DUE" 6163 * "RDATE" 6165 * "RRULE" 6167 * "EXDATE" 6169 * "EXRULE" 6170 * "STATUS" 6172 In addition, changes made by the "Organizer" to other properties 6173 can also force the sequence number to be incremented. The 6174 "Organizer" CUA MUST increment the sequence number when ever it 6175 makes changes to properties in the calendar component that the 6176 "Organizer" deems will jeopardize the validity of the 6177 participation status of the "Attendees". For example, changing 6178 the location of a meeting from one locale to another distant 6179 locale could effectively impact the participation status of the 6180 "Attendees". 6182 The "Organizer" includes this property in an iCalendar object that 6183 it sends to an "Attendee" to specify the current version of the 6184 calendar component. 6186 The "Attendee" includes this property in an iCalendar object that 6187 it sends to the "Organizer" to specify the version of the calendar 6188 component that the "Attendee" is referring to. 6190 A change to the sequence number is not the mechanism that an 6191 "Organizer" uses to request a response from the "Attendees". The 6192 "RSVP" parameter on the "ATTENDEE" property is used by the 6193 "Organizer" to indicate that a response from the "Attendees" is 6194 requested. 6196 Format Definition: The property is defined by the following notation: 6198 seq = "SEQUENCE" seqparam ":" integer CRLF 6199 ; Default is "0" 6201 seqparam = *(";" xparam) 6203 Example: The following is an example of this property for a calendar 6204 component that was just created by the "Organizer". 6206 SEQUENCE:0 6208 The following is an example of this property for a calendar 6209 component that has been revised two different times by the 6210 "Organizer". 6212 SEQUENCE:2 6214 3.8.8. Miscellaneous Component Properties 6216 The following properties specify information about a number of 6217 miscellaneous features of calendar components. 6219 3.8.8.1. Non-standard Properties 6221 Property Name: Any property name with a "X-" prefix 6223 Purpose: This class of property provides a framework for defining 6224 non-standard properties. 6226 Value Type: TEXT 6228 Property Parameters: Non-standard and language property parameters 6229 can be specified on this property. 6231 Conformance: This property can be specified in any calendar 6232 component. 6234 Description: The MIME Calendaring and Scheduling Content Type 6235 provides a "standard mechanism for doing non-standard things". 6236 This extension support is provided for implementers to "push the 6237 envelope" on the existing version of the memo. Extension 6238 properties are specified by property and/or property parameter 6239 names that have the prefix text of "X-" (the two character 6240 sequence: LATIN CAPITAL LETTER X character followed by the HYPHEN- 6241 MINUS character). It is recommended that vendors concatenate onto 6242 this sentinel another short prefix text to identify the vendor. 6243 This will facilitate readability of the extensions and minimize 6244 possible collision of names between different vendors. User 6245 agents that support this content type are expected to be able to 6246 parse the extension properties and property parameters but can 6247 ignore them. 6249 At present, there is no registration authority for names of 6250 extension properties and property parameters. The data type for 6251 this property is TEXT. Optionally, the data type can be any of 6252 the other valid data types. 6254 Format Definition: The property is defined by the following notation: 6256 x-prop = x-name *(";" xparam) [";" languageparam] ":" text CRLF 6257 ; Lines longer than 75 octets should be folded 6259 Example: The following might be the ABC vendor's extension for an 6260 audio-clip form of subject property: 6262 X-ABC-MMSUBJ;X-ABC-MMSUBJTYPE=wave:http://load.noise.org/mysubj.wav 6264 3.8.8.2. Request Status 6266 Property Name: REQUEST-STATUS 6268 Purpose: This property defines the status code returned for a 6269 scheduling request. 6271 Value Type: TEXT 6273 Property Parameters: Non-standard and language property parameters 6274 can be specified on this property. 6276 Conformance: The property can be specified in "VEVENT", "VTODO", 6277 "VJOURNAL" or "VFREEBUSY" calendar component. 6279 Description: This property is used to return status code information 6280 related to the processing of an associated iCalendar object. The 6281 data type for this property is TEXT. 6283 The value consists of a short return status component, a longer 6284 return status description component, and optionally a status- 6285 specific data component. The components of the value are 6286 separated by the SEMICOLON character (US-ASCII decimal 59). 6288 The short return status is a PERIOD character (US-ASCII decimal 6289 46) separated 3-tuple of integers. For example, "3.1.1". The 6290 successive levels of integers provide for a successive level of 6291 status code granularity. 6293 The following are initial classes for the return status code. 6294 Individual iCalendar object methods will define specific return 6295 status codes for these classes. In addition, other classes for 6296 the return status code may be defined using the registration 6297 process defined later in this memo. 6299 |==============+===============================================| 6300 | Short Return | Longer Return Status Description | 6301 | Status Code | | 6302 |==============+===============================================| 6303 | 1.xx | Preliminary success. This class of status | 6304 | | of status code indicates that the request has | 6305 | | request has been initially processed but that | 6306 | | completion is pending. | 6307 |==============+===============================================| 6308 | 2.xx | Successful. This class of status code | 6309 | | indicates that the request was completed | 6310 | | successfuly. However, the exact status code | 6311 | | can indicate that a fallback has been taken. | 6312 |==============+===============================================| 6313 | 3.xx | Client Error. This class of status code | 6314 | | indicates that the request was not successful.| 6315 | | The error is the result of either a syntax or | 6316 | | a semantic error in the client formatted | 6317 | | request. Request should not be retried until | 6318 | | the condition in the request is corrected. | 6319 |==============+===============================================| 6320 | 4.xx | Scheduling Error. This class of status code | 6321 | | indicates that the request was not successful.| 6322 | | Some sort of error occurred within the | 6323 | | calendaring and scheduling service, not | 6324 | | directly related to the request itself. | 6325 |==============+===============================================| 6327 Format Definition: The property is defined by the following notation: 6329 rstatus = "REQUEST-STATUS" rstatparam ":" 6330 statcode ";" statdesc [";" extdata] 6332 rstatparam = *( 6334 ; the following is optional, 6335 ; but MUST NOT occur more than once 6337 (";" languageparm) / 6339 ; the following is optional, 6340 ; and MAY occur more than once 6342 (";" xparam) 6344 ) 6346 statcode = 1*DIGIT *("." 1*DIGIT) 6347 ;Hierarchical, numeric return status code 6349 statdesc = text 6350 ;Textual status description 6352 extdata = text 6353 ;Textual exception data. For example, the offending property 6354 ;name and value or complete property line. 6356 Example: The following are some possible examples of this property. 6358 The COMMA and SEMICOLON separator characters in the property value 6359 are BACKSLASH character escaped because they appear in a text 6360 value. 6362 REQUEST-STATUS:2.0;Success 6364 REQUEST-STATUS:3.1;Invalid property value;DTSTART:96-Apr-01 6366 REQUEST-STATUS:2.8; Success\, repeating event ignored. Scheduled 6367 as a single event.;RRULE:FREQ=WEEKLY\;INTERVAL=2 6369 REQUEST-STATUS:4.1;Event conflict. Date/time is busy. 6371 REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE: 6372 MAILTO:jsmith@example.com 6374 4. iCalendar Object Examples 6376 The following examples are provided as an informational source of 6377 illustrative iCalendar objects consistent with this content type. 6379 The following example specifies a three-day conference that begins at 6380 8:00 AM EDT, September 18, 1996 and end at 6:00 PM EDT, September 20, 6381 1996. 6383 BEGIN:VCALENDAR 6384 PRODID:-//xyz Corp//NONSGML PDA Calendar Version 1.0//EN 6385 VERSION:2.0 6386 BEGIN:VEVENT 6387 DTSTAMP:19960704T120000Z 6388 UID:uid1@example.com 6389 ORGANIZER:MAILTO:jsmith@example.com 6390 DTSTART:19960918T143000Z 6391 DTEND:19960920T220000Z 6392 STATUS:CONFIRMED 6393 CATEGORIES:CONFERENCE 6394 SUMMARY:Networld+Interop Conference 6395 DESCRIPTION:Networld+Interop Conference 6396 and Exhibit\nAtlanta World Congress Center\n 6397 Atlanta\, Georgia 6398 END:VEVENT 6399 END:VCALENDAR 6401 The following example specifies a group scheduled meeting that begin 6402 at 8:30 AM EST on March 12, 1998 and end at 9:30 AM EST on March 12, 6403 1998. The "Organizer" has scheduled the meeting with one or more 6404 calendar users in a group. A time zone specification for Eastern 6405 United States has been specified. 6407 BEGIN:VCALENDAR 6408 PRODID:-//RDU Software//NONSGML HandCal//EN 6409 VERSION:2.0 6410 BEGIN:VTIMEZONE 6411 TZID:US-Eastern 6412 BEGIN:STANDARD 6413 DTSTART:19981025T020000 6414 RDATE:19981025T020000 6415 TZOFFSETFROM:-0400 6416 TZOFFSETTO:-0500 6417 TZNAME:EST 6418 END:STANDARD 6419 BEGIN:DAYLIGHT 6420 DTSTART:19990404T020000 6421 RDATE:19990404T020000 6422 TZOFFSETFROM:-0500 6423 TZOFFSETTO:-0400 6424 TZNAME:EDT 6425 END:DAYLIGHT 6426 END:VTIMEZONE 6427 BEGIN:VEVENT 6428 DTSTAMP:19980309T231000Z 6429 UID:guid-1.example.com 6430 ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@example.com 6431 ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;CUTYPE=GROUP: 6432 MAILTO:employee-A@example.com 6433 DESCRIPTION:Project XYZ Review Meeting 6434 CATEGORIES:MEETING 6435 CLASS:PUBLIC 6436 CREATED:19980309T130000Z 6437 SUMMARY:XYZ Project Review 6438 DTSTART;TZID=US-Eastern:19980312T083000 6439 DTEND;TZID=US-Eastern:19980312T093000 6440 LOCATION:1CP Conference Room 4350 6441 END:VEVENT 6442 END:VCALENDAR 6444 The following is an example of an iCalendar object passed in a MIME 6445 message with a single body part consisting of a "text/calendar" 6446 Content Type. 6448 TO:jsmith@example.com 6449 FROM:jdoe@example.com 6450 MIME-VERSION:1.0 6451 MESSAGE-ID: 6452 CONTENT-TYPE:text/calendar; method="xyz"; component="VEVENT" 6454 BEGIN:VCALENDAR 6455 METHOD:xyz 6456 VERSION:2.0 6457 PRODID:-//ABC Corporation//NONSGML My Product//EN 6458 BEGIN:VEVENT 6459 DTSTAMP:19970324T120000Z 6460 SEQUENCE:0 6461 UID:uid3@example.com 6462 ORGANIZER:MAILTO:jdoe@example.com 6463 ATTENDEE;RSVP=TRUE:MAILTO:jsmith@example.com 6464 DTSTART:19970324T123000Z 6465 DTEND:19970324T210000Z 6466 CATEGORIES:MEETING,PROJECT 6467 CLASS:PUBLIC 6468 SUMMARY:Calendaring Interoperability Planning Meeting 6469 DESCRIPTION:Discuss how we can test c&s interoperability\n 6470 using iCalendar and other IETF standards. 6471 LOCATION:LDB Lobby 6472 ATTACH;FMTTYPE=application/postscript:ftp://example.com/pub/ 6473 conf/bkgrnd.ps 6474 END:VEVENT 6475 END:VCALENDAR 6477 The following is an example of a to-do due on April 15, 1998. An 6478 audio alarm has been specified to remind the calendar user at noon, 6479 the day before the to-do is expected to be completed and repeat 6480 hourly, four additional times. The to-do definition has been 6481 modified twice since it was initially created. 6483 BEGIN:VCALENDAR 6484 VERSION:2.0 6485 PRODID:-//ABC Corporation//NONSGML My Product//EN 6486 BEGIN:VTODO 6487 DTSTAMP:19980130T134500Z 6488 SEQUENCE:2 6489 UID:uid4@example.com 6490 ORGANIZER:MAILTO:unclesam@us.gov 6491 ATTENDEE;PARTSTAT=ACCEPTED:MAILTO:jqpublic@example.com 6492 DUE:19980415T235959 6493 STATUS:NEEDS-ACTION 6494 SUMMARY:Submit Income Taxes 6495 BEGIN:VALARM 6496 ACTION:AUDIO 6497 TRIGGER:19980403T120000Z 6498 ATTACH;FMTTYPE=audio/basic:http://example.com/pub/audio- 6499 files/ssbanner.aud 6500 REPEAT:4 6501 DURATION:PT1H 6502 END:VALARM 6503 END:VTODO 6504 END:VCALENDAR 6506 The following is an example of a journal entry. 6508 BEGIN:VCALENDAR 6509 VERSION:2.0 6510 PRODID:-//ABC Corporation//NONSGML My Product//EN 6511 BEGIN:VJOURNAL 6512 DTSTAMP:19970324T120000Z 6513 UID:uid5@example.com 6514 ORGANIZER:MAILTO:jsmith@example.com 6515 STATUS:DRAFT 6516 CLASS:PUBLIC 6517 CATEGORIES:Project Report,XYZ,Weekly Meeting 6518 DESCRIPTION:Project xyz Review Meeting Minutes\n 6519 Agenda\n1. Review of project version 1.0 requirements.\n2. 6520 Definition 6521 of project processes.\n3. Review of project schedule.\n 6522 Participants: John Smith\, Jane Doe\, Jim Dandy\n-It was 6523 decided that the requirements need to be signed off by 6524 product marketing.\n-Project processes were accepted.\n 6525 -Project schedule needs to account for scheduled holidays 6526 and employee vacation time. Check with HR for specific 6527 dates.\n-New schedule will be distributed by Friday.\n- 6528 Next weeks meeting is cancelled. No meeting until 3/23. 6529 END:VJOURNAL 6530 END:VCALENDAR 6532 The following is an example of published busy time information. The 6533 iCalendar object might be placed in the network resource 6534 http://www.example.com/calendar/busytime/jsmith.ifb. 6536 BEGIN:VCALENDAR 6537 VERSION:2.0 6538 PRODID:-//RDU Software//NONSGML HandCal//EN 6539 BEGIN:VFREEBUSY 6540 ORGANIZER:MAILTO:jsmith@example.com 6541 DTSTART:19980313T141711Z 6542 DTEND:19980410T141711Z 6543 FREEBUSY:19980314T233000Z/19980315T003000Z 6544 FREEBUSY:19980316T153000Z/19980316T163000Z 6545 FREEBUSY:19980318T030000Z/19980318T040000Z 6546 URL:http://www.example.com/calendar/busytime/jsmith.ifb 6547 END:VFREEBUSY 6548 END:VCALENDAR 6550 5. Recommended Practices 6552 These recommended practices should be followed in order to assure 6553 consistent handling of the following cases for an iCalendar object. 6555 1. Content lines longer than 75 octets SHOULD be folded. 6557 2. A calendar entry with a "DTSTART" property but no "DTEND" 6558 property does not take up any time. It is intended to represent 6559 an event that is associated with a given calendar date and time 6560 of day, such as an anniversary. Since the event does not take 6561 up any time, it MUST NOT be used to record busy time no matter 6562 what the value for the "TRANSP" property. 6564 3. When the "DTSTART" and "DTEND", for "VEVENT", "VJOURNAL" and 6565 "VFREEBUSY" calendar components, and "DTSTART" and "DUE", for 6566 "VTODO" calendar components, have the same value data type 6567 (e.g., DATE-TIME), they SHOULD specify values in the same time 6568 format (e.g., UTC time format). 6570 4. When the combination of the "RRULE" and "RDATE" properties on an 6571 iCalendar object produces multiple instances having the same 6572 start date/time, they should be collapsed to, and considered as, 6573 a single instance. 6575 5. When a calendar user receives multiple requests for the same 6576 calendar component (e.g., REQUEST for a "VEVENT" calendar 6577 component) as a result of being on multiple mailing lists 6578 specified by "ATTENDEE" properties in the request, they SHOULD 6579 respond to only one of the requests. The calendar user SHOULD 6580 also specify (using the "MEMBER" parameter of the "ATTENDEE" 6581 property) which mailing list they are a member of. 6583 6. An implementation can truncate a "SUMMARY" property value to 255 6584 octets, but MUST NOT truncate the value in the middle of a UTF-8 6585 multi-octet sequence . 6587 7. If seconds of the minute are not supported by an implementation, 6588 then a value of "00" SHOULD be specified for the seconds 6589 component in a time value. 6591 8. If the value type parameter (VALUE=) contains an unknown value 6592 type, it SHOULD be treated as TEXT. 6594 9. TZURL values SHOULD NOT be specified as a FILE URI type. This 6595 URI form can be useful within an organization, but is 6596 problematic in the Internet. 6598 10. Some possible English values for CATEGORIES property include 6599 "ANNIVERSARY", "APPOINTMENT", "BUSINESS", "EDUCATION", 6600 "HOLIDAY", "MEETING", "MISCELLANEOUS", "NON-WORKING HOURS", "NOT 6601 IN OFFICE", "PERSONAL", "PHONE CALL", "SICK DAY", "SPECIAL 6602 OCCASION", "TRAVEL", "VACATION". Categories can be specified in 6603 any registered language. 6605 11. Some possible English values for RESOURCES property include 6606 "CATERING", "CHAIRS", "COMPUTER PROJECTOR", "EASEL", "OVERHEAD 6607 PROJECTOR", "SPEAKER PHONE", "TABLE", "TV", "VCR", "VIDEO 6608 PHONE", "VEHICLE". Resources can be specified in any registered 6609 language. 6611 6. Registration of Content Type Elements 6613 This section provides the process for registration of MIME 6614 Calendaring and Scheduling Content Type iCalendar object methods and 6615 new or modified properties. 6617 6.1. Registration of New and Modified iCalendar Object Methods 6619 New MIME Calendaring and Scheduling Content Type iCalendar object 6620 methods are registered by the publication of an IETF Request for 6621 Comments (RFC). Changes to an iCalendar object method are registered 6622 by the publication of a revision of the RFC defining the method. 6624 6.2. Registration of New Properties 6626 This section defines procedures by which new properties or enumerated 6627 property values for the MIME Calendaring and Scheduling Content Type 6628 can be registered with the IANA. Non-IANA properties can be used by 6629 bilateral agreement, provided the associated properties names follow 6630 the "X-" convention. 6632 The procedures defined here are designed to allow public comment and 6633 review of new properties, while posing only a small impediment to the 6634 definition of new properties. 6636 Registration of a new property is accomplished by the following 6637 steps. 6639 6.2.1. Define the property 6641 A property is defined by completing the following template. 6643 To: ietf-calendar@imc.org 6645 Subject: Registration of text/calendar MIME property XXX 6647 Property name: 6649 Property purpose: 6651 Property value type(s): 6653 Property parameter (s): 6655 Conformance: 6657 Description: 6659 Format definition: 6661 Examples: 6663 The meaning of each field in the template is as follows. 6665 Property name: The name of the property, as it will appear in the 6666 body of an text/calendar MIME Content-Type "property: value" line 6667 to the left of the colon ":". 6669 Property purpose: The purpose of the property (e.g., to indicate a 6670 delegate for the event or to-do, etc.). Give a short but clear 6671 description. 6673 Property value type (s): Any of the valid value types for the 6674 property value needs to be specified. The default value type also 6675 needs to be specified. If a new value type is specified, it needs 6676 to be declared in this section. 6678 Property parameter (s): Any of the valid property parameters for the 6679 property needs to be specified. 6681 Conformance: The calendar components that the property can appear in 6682 needs to be specified. 6684 Description: Any special notes about the property, how it is to be 6685 used, etc. 6687 Format definition: The ABNF for the property definition needs to be 6688 specified. 6690 Examples: One or more examples of instances of the property needs to 6691 be specified. 6693 6.2.2. Post the Property definition 6695 The property description MUST be posted to the new property 6696 discussion list, ietf-calendar@imc.org. 6698 6.2.3. Allow a comment period 6700 Discussion on the new property MUST be allowed to take place on the 6701 list for a minimum of two weeks. Consensus MUST be reached on the 6702 property before proceeding to the next step. 6704 6.2.4. Submit the property for approval 6706 Once the two-week comment period has elapsed, and the proposer is 6707 convinced consensus has been reached on the property, the 6708 registration application should be submitted to the Method Reviewer 6709 for approval. The Method Reviewer is appointed by the Application 6710 Area Directors and can either accept or reject the property 6711 registration. An accepted registration should be passed on by the 6712 Method Reviewer to the IANA for inclusion in the official IANA method 6713 registry. The registration can be rejected for any of the following 6714 reasons. 1) Insufficient comment period; 2) Consensus not reached; 3) 6715 Technical deficiencies raised on the list or elsewhere have not been 6716 addressed. The Method Reviewer's decision to reject a property can 6717 be appealed by the proposer to the IESG, or the objections raised can 6718 be addressed by the proposer and the property resubmitted. 6720 6.3. Property Change Control 6722 Existing properties can be changed using the same process by which 6723 they were registered. 6725 1. Define the change 6727 2. Post the change 6729 3. Allow a comment period 6731 4. Submit the property for approval 6733 Note that the original author or any other interested party can 6734 propose a change to an existing property, but that such changes 6735 should only be proposed when there are serious omissions or errors in 6736 the published memo. The Method Reviewer can object to a change if it 6737 is not backward compatible, but is not required to do so. 6739 Property definitions can never be deleted from the IANA registry, but 6740 properties which are no longer believed to be useful can be declared 6741 OBSOLETE by a change to their "intended use" field. 6743 7. Internationalization Considerations 6745 8. Security Considerations 6747 SPOOFING: In this memo, the "Organizer" is the only person authorized 6748 to make changes to an existing "VEVENT", "VTODO", "VJOURNAL" 6749 calendar component and redistribute the updates to the 6750 "Attendees". An iCalendar object that maliciously changes or 6751 cancels an existing "VEVENT", "VTODO" or "VJOURNAL" or "VFREEBUSY" 6752 calendar component might be constructed by someone other than the 6753 "Organizer" and sent to the "Attendees". In addition in this 6754 memo, other than the "Organizer", an "Attendee" of a "VEVENT", 6755 "VTODO", "VJOURNAL" calendar component is the only other person 6756 authorized to update any parameter associated with their 6757 "ATTENDEE" property and send it to the "Organizer". An iCalendar 6758 object that maliciously changes the "ATTENDEE" parameters can be 6759 constructed by someone other than the real "Attendee" and sent to 6760 the "Organizer". 6762 PROCEDURAL ALARMS: An iCalendar object can be created that contains a 6763 "VEVENT" and "VTODO" calendar component with "VALARM" calendar 6764 components. The "VALARM" calendar component can be of type 6765 PROCEDURE and can have an attachment containing some sort of 6766 executable program. Implementations that incorporate these types 6767 of alarms are subject to any virus or malicious attack that might 6768 occur as a result of executing the attachment. 6770 ATTACHMENTS: An iCalendar object can include references to Uniform 6771 Resource Locators that can be programmed resources. 6773 Implementers and users of this memo should be aware of the network 6774 security implications of accepting and parsing such information. 6775 In addition, the security considerations observed by 6776 implementations of electronic mail systems should be followed for 6777 this memo. 6779 9. IANA Consideration 6781 9.1. Media Type Registration Information 6783 The Calendaring and Scheduling Core Object Specification is intended 6784 for use as a MIME content type. However, the implementation of the 6785 memo is in no way limited solely as a MIME content type. 6787 To: ietf-types@iana.org 6788 Subject: Registration of media type text/calendar 6790 Type name: text 6792 Subtype name: calendar 6794 Required parameters: none 6796 Optional parameters: charset, method, component and optinfo 6798 The "charset" parameter is defined in [RFC2046] for subtypes of 6799 the "text" media type. It is used to indicate the charset used in 6800 the body part. The charset supported by this revision of 6801 iCalendar is UTF-8. The use of any other charset is deprecated by 6802 this revision of iCalendar; however note that this revision 6803 requires that compliant applications MUST accept iCalendar objects 6804 using either the UTF-8 or US-ASCII charset. 6806 The "method" parameter is used to convey the iCalendar object 6807 method or transaction semantics for the calendaring and scheduling 6808 information. It also is an identifier for the restricted set of 6809 properties and values that the iCalendar object consists of. The 6810 parameter is to be used as a guide for applications interpreting 6811 the information contained within the body part. It SHOULD NOT be 6812 used to exclude or require particular pieces of information unless 6813 the identified method definition specifically calls for this 6814 behavior. Unless specifically forbidden by a particular method 6815 definition, a text/calendar content type can contain any set of 6816 properties permitted by the Calendaring and Scheduling Core Object 6817 Specification. The "method" parameter MUST be the same value as 6818 that specified in the "METHOD" component property in the iCalendar 6819 object. If one is present, the other MUST also be present. 6821 The value for the "method" parameter is defined as follows: 6823 method = 1*(ALPHA / DIGIT / "-") 6824 ; IANA registered iCalendar object method 6826 The "component" parameter conveys the type of iCalendar calendar 6827 component within the body part. If the iCalendar object contains 6828 more than one calendar component type, then multiple component 6829 parameters MUST be specified. 6831 The value for the "component" parameter is defined as follows: 6833 component = "VEVENT" 6834 / "VTODO" 6835 / "VJOURNAL" 6836 / "VFREEBUSY" 6837 / "VTIMEZONE" 6838 / x-name 6839 / iana-token 6841 The "optinfo" parameter conveys optional information about the 6842 iCalendar object within the body part. This parameter can only 6843 specify semantics already specified by the iCalendar object and 6844 that can be otherwise determined by parsing the body part. In 6845 addition, the optional information specified by this parameter 6846 MUST be consistent with that information specified by the 6847 iCalendar object. For example, it can be used to convey the 6848 "Attendee" response status to a meeting request. The parameter 6849 value consists of a string value. 6851 The parameter can be specified multiple times. 6853 This parameter MAY only specify semantics already specified by the 6854 iCalendar object and that can be otherwise determined by parsing 6855 the body part. 6857 The value for the "optinfo" parameter is defined as follows: 6859 optinfo = infovalue / qinfovalue 6861 infovalue = iana-token / x-name 6863 qinfovalue = DQUOTE (infovalue) DQUOTE 6865 Encoding considerations: This media type can contain 8bit characters, 6866 so the use of quoted-printable or base64 MIME Content-Transfer- 6867 Encodings might be necessary when iCalendar objects are 6868 transferred across protocols restricted to the 7bit repertoire. 6869 Note that a text valued property in the content entity can also 6870 have content encoding of special characters using a BACKSLASH 6871 character (US-ASCII decimal 92) escapement technique. This means 6872 that content values can end up encoded twice. 6874 Security considerations: See Section 8. 6876 Interoperability considerations: This media type is intended to 6877 define a common format for conveying calendaring and scheduling 6878 information between different systems. It is heavily based on the 6879 earlier [VCAL] industry specification. 6881 Published specification: This specification. 6883 Applications which use this media type: This media type is designed 6884 for widespread use by Internet calendaring and scheduling 6885 applications. In addition, applications in the workflow and 6886 document management area might find this content-type applicable. 6887 The iTIP [I-D.ietf-calsify-2446bis], iMIP [I-D.ietf-calsify- 6888 rfc2447bis] and CalDAV [I-D.dusseault-caldav] Internet protocols 6889 directly use this media type also. 6891 Additional information: 6893 Magic number(s): None. 6895 File extension(s): The file extension of "ics" is to be used to 6896 designate a file containing (an arbitrary set of) calendaring 6897 and scheduling information consistent with this MIME content 6898 type. 6900 The file extension of "ifb" is to be used to designate a file 6901 containing free or busy time information consistent with this 6902 MIME content type. 6904 Macintosh file type code(s): The file type code of "iCal" is to be 6905 used in Apple MacIntosh operating system environments to 6906 designate a file containing calendaring and scheduling 6907 information consistent with this MIME media type. 6909 The file type code of "iFBf" is to be used in Apple MacIntosh 6910 operating system environments to designate a file containing 6911 free or busy time information consistent with this MIME media 6912 type. 6914 Person & email address to contact for further information: TBD 6916 Intended usage: COMMON 6918 Restrictions on usage: There are no restrictions on where this media 6919 type can be used. 6921 Author: TBD 6923 Change controller: IETF 6925 10. Acknowledgments 6927 The editor of this document wish to thank Frank Dawson and Stenerson 6928 Derik, the original authors of RFC2445, as well as the following 6929 individuals who have participated in the drafting, review and 6930 discussion of this memo: 6932 Joe Abley, Hervey Allen, Jay Batson, Oliver Block, Chris Bryant, 6933 Tantek Celik, Mark Crispin, Cyrus Daboo, Mike Douglass, Andrew N. 6934 Dowden, Lisa Dusseault, Ned Freed, Ted Hardie, Tim Hare, Jeffrey 6935 Harris, Helge Hess, Leif Johansson, Reinhold Kainhofer, Eliot Lear, 6936 Jeff McCullough, Bill McQuillan, Alexey Melnikov, Aki Niemi, John W. 6937 Noerenberg II, Chuck Norris, Mark Paterson, Simon Pilette, Arnaud 6938 Quillaud, Robert Ransdell, Julian F. Reschke, Caleb Richardson, Sam 6939 Roberts, George Sexton, Simon Vaillancourt, Michiel van Leeuwen, and 6940 Sandy Wills. 6942 The editor would also like to thank the Calendaring and Scheduling 6943 Consortium for advice with this specification, and for organizing 6944 interoperability testing events to help refine it. 6946 11. References 6948 11.1. Normative References 6950 [ISO.8601.1988] 6951 International Organization for Standardization, "Data 6952 elements and interchange formats - Information interchange 6953 - Representation of dates and times", 6954 . 6956 [ISO.9070.1991] 6957 International Organization for Standardization, 6958 "Information Technology_SGML Support Facilities -- 6959 Registration Procedures for Public Text Owner Identifiers, 6960 Second Edition", April 1991, . 6963 [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6964 Extensions (MIME) Part One: Format of Internet Message 6965 Bodies", RFC 2045, November 1996. 6967 [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6968 Extensions (MIME) Part Two: Media Types", RFC 2046, 6969 November 1996. 6971 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6972 Requirement Levels", BCP 14, RFC 2119, March 1997. 6974 [RFC2368] Hoffman, P., Masinter, L., and J. Zawinski, "The mailto 6975 URL scheme", RFC 2368, July 1998. 6977 [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, 6978 April 2001. 6980 [RFC3066] Alvestrand, H., "Tags for the Identification of 6981 Languages", BCP 47, RFC 3066, January 2001. 6983 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 6984 10646", STD 63, RFC 3629, November 2003. 6986 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 6987 Resource Identifier (URI): Generic Syntax", STD 66, 6988 RFC 3986, January 2005. 6990 [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6991 Specifications: ABNF", RFC 4234, October 2005. 6993 11.2. Informative References 6995 [I-D.dusseault-caldav] 6996 Daboo, C., Desruisseaux, B., and L. Dusseault, 6997 "Calendaring Extensions to WebDAV (CalDAV)", 6998 draft-dusseault-caldav-15 (work in progress), 6999 September 2006. 7001 [I-D.ietf-calsify-2446bis] 7002 Daboo, C., "iCalendar Transport-Independent 7003 Interoperability Protocol (iTIP)", 7004 draft-ietf-calsify-2446bis-02 (work in progress), 7005 June 2006. 7007 [I-D.ietf-calsify-rfc2447bis] 7008 Melnikov, A., "iCalendar Message-Based Interoperability 7009 Protocol(iMIP)", draft-ietf-calsify-rfc2447bis-02 (work in 7010 progress), June 2006. 7012 [RFC2425] Howes, T., Smith, M., and F. Dawson, "A MIME Content-Type 7013 for Directory Information", RFC 2425, September 1998. 7015 [RFC2426] Dawson, F. and T. Howes, "vCard MIME Directory Profile", 7016 RFC 2426, September 1998. 7018 [TZDB] "Time zone code and data", October 2005, 7019 . 7021 [VCAL] Internet Mail Consortium, "vCalendar: The Electronic 7022 Calendaring and Scheduling Exchange Format", 7023 September 1996, . 7025 URIs 7027 [1] 7029 Appendix A. Change Log (to be removed by RFC Editor before publication) 7031 A.1. Changes in -02 7033 A detailed list of changes is available at the following page: 7034 http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/ 7035 draft-ietf-calsify-rfc2445bis-02.html. 7037 a. Numerous editorial changes including the typos listed in the 7038 "RFC2445 Errata": 7039 http://www.rfc-editor.org/cgi-bin/errataSearch.pl?rfc=2445& 7040 and in the "RFC2445 Issues List": 7041 http://www.softwarestudio.org/iCal/2445Issues.html. 7043 b. Clarified line folding requirements. 7045 c. Clarified charset requirements. 7047 d. Clarified line limits requirements. 7049 e. Clarified on the use of the LANGUAGE parameter. 7051 f. Fixed the eventprop, todoprop and jourprop ABNF rules with 7052 respect to required properties. 7054 g. Fixed all the examples to use RFC2606-compliant FQDNs. 7056 h. Fixed the Content-ID URLs in the examples. 7058 i. Fixed the LDAP URLs in the examples. 7060 j. Moved multiple references in the Informative References section. 7062 k. Updated the Acknowledgments section. 7064 A.2. Changes in -01 7066 A detailed list of changes is available at the following page: 7067 http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/ 7068 draft-ietf-calsify-rfc2445bis-01.html. 7070 a. Numerous editorial changes (typos, errors in examples, etc.). 7072 b. Fixed invalid media types in examples. 7074 c. Fixed the DTSTAMP values in the examples. 7076 d. Moved media type registration in a separate IANA Consideration 7077 section. 7079 e. Added Internationalization Considerations section. 7081 f. Added Security Considerations section. 7083 g. Updated the Acknowledgments section. 7085 Author's Address 7087 Bernard Desruisseaux (editor) 7088 Oracle Corporation 7089 600 blvd. de Maisonneuve West 7090 Suite 1900 7091 Montreal, QC H3A 3J2 7092 CA 7094 Email: bernard.desruisseaux@oracle.com 7095 URI: http://www.oracle.com/ 7097 Intellectual Property Statement 7099 The IETF takes no position regarding the validity or scope of any 7100 Intellectual Property Rights or other rights that might be claimed to 7101 pertain to the implementation or use of the technology described in 7102 this document or the extent to which any license under such rights 7103 might or might not be available; nor does it represent that it has 7104 made any independent effort to identify any such rights. Information 7105 on the procedures with respect to rights in RFC documents can be 7106 found in BCP 78 and BCP 79. 7108 Copies of IPR disclosures made to the IETF Secretariat and any 7109 assurances of licenses to be made available, or the result of an 7110 attempt made to obtain a general license or permission for the use of 7111 such proprietary rights by implementers or users of this 7112 specification can be obtained from the IETF on-line IPR repository at 7113 http://www.ietf.org/ipr. 7115 The IETF invites any interested party to bring to its attention any 7116 copyrights, patents or patent applications, or other proprietary 7117 rights that may cover technology that may be required to implement 7118 this standard. Please address the information to the IETF at 7119 ietf-ipr@ietf.org. 7121 Disclaimer of Validity 7123 This document and the information contained herein are provided on an 7124 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 7125 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 7126 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 7127 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 7128 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 7129 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 7131 Copyright Statement 7133 Copyright (C) The Internet Society (2006). This document is subject 7134 to the rights, licenses and restrictions contained in BCP 78, and 7135 except as set forth therein, the authors retain all their rights. 7137 Acknowledgment 7139 Funding for the RFC Editor function is currently provided by the 7140 Internet Society.