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Murchison, Ed. 5 Intended status: Standards Track Fastmail 6 Expires: May 29, 2021 November 25, 2020 8 VALARM Extensions for iCalendar 9 draft-ietf-calext-valarm-extensions-03 11 Abstract 13 This document defines a set of extensions to the iCalendar VALARM 14 component to enhance use of alarms and improve interoperability 15 between clients and servers. 17 This document updates RFC5545. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on May 29, 2021. 36 Copyright Notice 38 Copyright (c) 2020 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 55 3. Extensible syntax for VALARM . . . . . . . . . . . . . . . . 3 56 4. Alarm Unique Identifier . . . . . . . . . . . . . . . . . . . 5 57 5. Alarm Related To . . . . . . . . . . . . . . . . . . . . . . 6 58 6. Alarm Acknowledgement . . . . . . . . . . . . . . . . . . . . 6 59 6.1. Acknowledged Property . . . . . . . . . . . . . . . . . . 7 60 7. Snoozing Alarms . . . . . . . . . . . . . . . . . . . . . . . 8 61 7.1. Relationship Type Property Parameter . . . . . . . . . . 9 62 8. Alarm Proximity Trigger . . . . . . . . . . . . . . . . . . . 9 63 8.1. Proximity Property . . . . . . . . . . . . . . . . . . . 10 64 8.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 11 65 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 66 10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 11 67 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 68 11.1. Property Registrations . . . . . . . . . . . . . . . . . 12 69 11.2. Relationship Types Registry . . . . . . . . . . . . . . 12 70 11.3. Proximity Value Registry . . . . . . . . . . . . . . . . 12 71 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 72 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 73 13.1. Normative References . . . . . . . . . . . . . . . . . . 13 74 13.2. Informative References . . . . . . . . . . . . . . . . . 13 75 13.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 14 76 Appendix A. Change History (To be removed by RFC Editor before 77 publication) . . . . . . . . . . . . . . . . . . . . 14 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 80 1. Introduction 82 The iCalendar [RFC5545] specification defines a set of components 83 used to describe calendar data. One of those is the "VALARM" 84 component which appears as a sub-component of "VEVENT" and "VTODO" 85 components. The "VALARM" component is used to specify a reminder for 86 an event or task. Different alarm actions are possible, as are 87 different ways to specify how the alarm is triggered. 89 As iCalendar has become more widely used and as client-server 90 protocols such as CalDAV [RFC4791] have become more prevalent, 91 several issues with "VALARM" components have arisen. Most of these 92 relate to the need to extend the existing "VALARM" component with new 93 properties and behaviors to allow clients and servers to accomplish 94 specific tasks in an interoperable manner. For example, clients 95 typically need a way to specify that an alarm has been dismissed by a 96 calendar user, or has been "snoozed" by a set amount of time. To 97 date, this has been done through the use of custom "X-" properties 98 specific to each client implementation, leading to poor 99 interoperability. 101 This specification defines a set of extensions to "VALARM" components 102 to cover common requirements for alarms not currently addressed in 103 iCalendar. Each extension is defined in a separate section below. 104 For the most part, each extension can be supported independently of 105 the others, though in some cases one extension will require another. 106 In addition, this specification describes mechanisms by which clients 107 can interoperably implement common features such as "snoozing". 109 2. Conventions Used in This Document 111 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 112 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 113 "OPTIONAL" in this document are to be interpreted as described in BCP 114 14 [1] [RFC2119] [RFC8174] when, and only when, they appear in all 115 capitals, as shown here. 117 When XML element types in the namespaces "DAV:" and 118 "urn:ietf:params:xml:ns:caldav" are referenced in this document 119 outside of the context of an XML fragment, the string "DAV:" and 120 "CALDAV:" will be prefixed to the element type names respectively. 122 3. Extensible syntax for VALARM 124 Section 3.6.6 of [RFC5545] defines the syntax for "VALARM" components 125 and properties within them. However, as written, it is hard to 126 extend this by adding, e.g., a new property common to all types of 127 alarm. Since many of the extensions defined in this document need to 128 extend the base syntax, an alternative form for the base syntax is 129 defined here, with the goal of simplifying specification of the 130 extensions. 132 A "VALARM" calendar component is re-defined by the following 133 notation: 135 alarmcext = "BEGIN" ":" "VALARM" CRLF 136 alarmprop 137 "END" ":" "VALARM" CRLF 139 alarmprop = *( 141 ; the following are REQUIRED, 142 ; but MUST NOT occur more than once 143 action / trigger / 145 ; one set of action properties MUST be 146 ; present and MUST match the action specified 147 ; in the ACTION property 149 actionprops / 151 ; the following is OPTIONAL, 152 ; and MAY occur more than once 154 x-prop / iana-prop 156 ) 158 actionprops = audiopropext / disppropext / emailpropext 160 audiopropext = *( 162 ; 'duration' and 'repeat' are both OPTIONAL, 163 ; and MUST NOT occur more than once each, 164 ; but if one occurs, so MUST the other 166 duration / repeat / 168 ; the following is OPTIONAL, 169 ; but MUST NOT occur more than once 171 attach 173 ) 175 disppropext = *( 177 ; the following are REQUIRED, 178 ; but MUST NOT occur more than once 180 description / 182 ; 'duration' and 'repeat' are both OPTIONAL, 183 ; and MUST NOT occur more than once each, 184 ; but if one occurs, so MUST the other 186 duration / repeat 188 ) 190 emailpropext = *( 191 ; the following are all REQUIRED, 192 ; but MUST NOT occur more than once 194 description / summary / 196 ; the following is REQUIRED, 197 ; and MAY occur more than once 199 attendee / 201 ; 'duration' and 'repeat' are both OPTIONAL, 202 ; and MUST NOT occur more than once each, 203 ; but if one occurs, so MUST the other 205 duration / repeat 207 ; the following is OPTIONAL, 208 ; and MAY occur more than once 210 attach 212 ) 214 4. Alarm Unique Identifier 216 This extension adds a "UID" property to "VALARM" components to allow 217 a unique identifier to be specified. The value of this property can 218 then be used to refer uniquely to the "VALARM" component. 220 The "UID" property defined here follows the definition in 221 Section 3.8.4.7 of [RFC5545] with the security and privacy updates in 222 Section 5.3 of [RFC7986]. In particular it MUST be a globally unique 223 identifier that does not contain any security- or privacy-sensitive 224 information. 226 The "VALARM" component defined in Section 3 is extended here as: 228 alarmprop /= *( 230 ; the following is OPTIONAL, 231 ; but MUST NOT occur more than once 233 uid 235 ) 237 5. Alarm Related To 239 It is often convenient to relate one or more "VALARM" components to 240 other "VALARM" components (e.g., see Section 7). This can be 241 accomplished if the "VALARM" components each have their own "UID" 242 property (as per Section 4). 244 This specification updates the usage of the "RELATED-TO" property 245 defined in Section 3.8.4.5 of [RFC5545] to enable its use with 246 "VALARM" components. Specific types of relationships between 247 "VALARM" components can be identified by registering new values for 248 the "RELTYPE" property parameter defined in Section 3.2.15 of 249 [RFC5545]. 251 The "VALARM" component defined in Section 3 is extended here as: 253 alarmprop /= *( 255 ; the following is OPTIONAL, 256 ; but MAY occur more than once 258 related 260 ) 262 6. Alarm Acknowledgement 264 There is currently no way for a "VALARM" component to indicate 265 whether it has been triggered and acknowledged. With the advent of a 266 standard client/server protocol for calendaring and scheduling data 267 ([RFC4791]) it is quite possible for an event with an alarm to exist 268 on multiple clients in addition to the server. If each of those is 269 responsible for performing the action when an alarm triggers, then 270 multiple "alerts" are generated by different devices. In such a 271 situation, a calendar user would like to be able to "dismiss" the 272 alarm on one device and have it automatically dismissed on the others 273 too. 275 Also, with recurring events that have alarms, it is important to know 276 when the last alarm in the recurring set was acknowledged, so that 277 the client can determine whether past alarms have been missed. 279 To address these needs, this specification adds an "ACKNOWLEDGED" 280 property to "VALARM" components to indicate when the alarm was last 281 sent or acknowledged. This is defined by the syntax below. 283 alarmprop /= *( 285 ; the following is OPTIONAL, 286 ; but MUST NOT occur more than once 288 acknowledged 290 ) 292 6.1. Acknowledged Property 294 Property Name: ACKNOWLEDGED 296 Purpose: This property specifies the UTC date and time at which the 297 corresponding alarm was last sent or acknowledged. 299 Value Type: DATE-TIME 301 Property Parameters: IANA and non-standard property parameters can 302 be specified on this property. 304 Conformance: This property can be specified within "VALARM" calendar 305 components. 307 Description: This property is used to specify when an alarm was last 308 sent or acknowledged. This allows clients to determine when a 309 pending alarm has been acknowledged by a calendar user so that any 310 alerts can be dismissed across multiple devices. It also allows 311 clients to track repeating alarms or alarms on recurring events or 312 to-dos to ensure that the right number of missed alarms can be 313 tracked. 315 Clients SHOULD set this property to the current date-time value in 316 UTC when a calendar user acknowledges a pending alarm. Certain 317 kinds of alarm may not provide feedback as to when the calendar 318 user sees them, for example email based alerts. For those kinds 319 of alarms, the client SHOULD set this property when the alarm is 320 triggered and the action successfully carried out. 322 When an alarm is triggered on a client, clients can check to see 323 if an "ACKNOWLEDGED" property is present. If it is, and the value 324 of that property is greater than or equal to the computed trigger 325 time for the alarm, then the client SHOULD NOT trigger the alarm. 326 Similarly, if an alarm has been triggered and an "alert" presented 327 to a calendar user, clients can monitor the iCalendar data to 328 determine whether an "ACKNOWLEDGED" property is added or changed 329 in the alarm component. If the value of any "ACKNOWLEDGED" 330 property in the alarm changes and is greater than or equal to the 331 trigger time of the alarm, then clients SHOULD dismiss or cancel 332 any "alert" presented to the calendar user. 334 Format Definition: This property is defined by the following 335 notation: 337 acknowledged = "ACKNOWLEDGED" acknowledgedparam ":" datetime CRLF 339 acknowledgedparam = *( 341 ; the following is OPTIONAL, 342 ; and MAY occur more than once 344 (";" other-param) 346 ) 348 Example: The following is an example of this property: 350 ACKNOWLEDGED:20090604T084500Z 352 7. Snoozing Alarms 354 Users often want to "snooze" an alarm, and this specification defines 355 a standard approach to accomplish that. 357 To "snooze" an alarm, clients create a new "VALARM" component within 358 the parent component of the "VALARM" that was triggered and is being 359 "snoozed" (i.e., as a "sibling" component of the "VALARM" being 360 snoozed). The new "VALARM" MUST be set to trigger at the user's 361 chosen "snooze" interval after the original alarm triggered. Clients 362 SHOULD use an absolute "TRIGGER" property with a "DATE-TIME" value 363 specified in UTC. 365 Clients SHOULD add a "RELATED-TO" property to the new "VALARM" 366 component with a value set to the "UID" property value of the 367 "VALARM" component being snoozed. If the "VALARM" component being 368 snoozed does not already have a "UID" property, the client SHOULD add 369 one. The "RELATED-TO" property added to the new "VALARM" component 370 SHOULD include a "RELTYPE" property parameter with a value set to 371 "SNOOZE". 373 When the "snooze" alarm is triggered and dismissed the client SHOULD 374 remove the corresponding "VALARM" component, or set the 375 "ACKNOWLEDGED" property (see Section 6.1). Alternatively, if the 376 "snooze" alarm is itself "snoozed", the client SHOULD remove the 377 original "snooze" alarm and create a new one, with the appropriate 378 trigger time and relationship set. 380 7.1. Relationship Type Property Parameter 382 This specification adds the "SNOOZE" relationship type for use with 383 the "RELTYPE" property defined in Section 3.2.15 of [RFC5545]. This 384 is used to relate a "snoozed" "VALARM" component to the original 385 alarm that the "snooze" was generated for. 387 8. Alarm Proximity Trigger 389 VALARMs are currently triggered when a specific date-time is reached. 390 It is also desirable to be able to trigger alarms based on location, 391 e.g. when arriving at or departing from a particular location. 393 This specification adds the following properties to "VALARM" 394 components to indicate when an alarm can be triggered based on 395 location. 397 "PROXIMITY" - indicates that a location based trigger is to be 398 used and which direction of motion is used for the trigger 400 "STRUCTURED-LOCATION" [I-D.ietf-calext-eventpub-extensions] - used 401 to indicate the actual location to trigger off, specified using a 402 geo: URI [RFC5870] which allows for two or three coordinate values 403 with an optional uncertainty 405 alarmprop /= *( 407 ; the following is OPTIONAL, 408 ; but MUST NOT occur more than once 410 proximity / 412 ; the following is OPTIONAL, 413 ; and MAY occur more than once, but only 414 ; when a PROXIMITY property is also present 416 structured-location 418 ) 420 Typically, when a "PROXIMITY" property is used there is no need to 421 specify a time-based trigger using the "TRIGGER" property. However, 422 since "TRIGGER" is defined as a required property for a "VALARM" 423 component, for backwards compatibility it has to be present, but 424 ignored. To indicate a "TRIGGER" that is to be ignored, clients 425 SHOULD use a value a long time in the past. A value of 426 "19760401T005545Z" has been commonly used for this purpose. 428 8.1. Proximity Property 430 Property Name: PROXIMITY 432 Purpose: This property indicates that a location based trigger is 433 applied to an alarm. 435 Value Type: TEXT 437 Property Parameters: IANA and non-standard property parameters can 438 be specified on this property. 440 Conformance: This property can be specified within "VALARM" calendar 441 components. 443 Description: This property is used to indicate that an alarm has a 444 location-based trigger. Its value identifies the direction of 445 motion used to trigger the alarm. One or more location values are 446 set using "STRUCTURED-LOCATION" properties. 448 When the property value is set to "ARRIVE", the alarm is triggered 449 when the calendar user agent arrives in the vicinity of any of the 450 specified locations. When set to "DEPART", the alarm is triggered 451 when the calendar user agent departs from the vicinity of any 452 specified locations. 454 When the property value is set to "CONNECT", the alarm is 455 triggered when the calendar user agent connects to a Bluetooth(R) 456 [BTcore]-enabled automobile. When set to "DISCONNECT", the alarm 457 is triggered when the calendar user agent disconnects from a 458 Bluetooth(R)-enabled automobile. 460 Format Definition: This property is defined by the following 461 notation: 463 proximity = "PROXIMITY" proximityparam ":" proximityvalue CRLF 465 proximityparam = *( 467 ; the following is OPTIONAL, 468 ; and MAY occur more than once 470 (";" other-param) 472 ) 474 proximityvalue = "ARRIVE" / "DEPART" / 475 "CONNECT" / "DISCONNECT" / iana-token / x-name 477 Example: The following is an example of this property: 479 PROXIMITY:ARRIVE 481 8.2. Example 483 The following example shows a "VALARM" component with a proximity 484 trigger set to trigger when the device running the calendar user 485 agent leaves the vicinity defined by the structured location 486 property. Note use of the "u=" parameter with the "geo" URI to 487 define the precision of the location determination. 489 BEGIN:VALARM 490 UID:77D80D14-906B-4257-963F-85B1E734DBB6 491 TRIGGER;VALUE=DATE-TIME:19760401T005545Z 492 ACTION:DISPLAY 493 DESCRIPTION:Remember to buy milk 494 TRIGGER;VALUE=DATE-TIME:19760401T005545Z 495 PROXIMITY:DEPART 496 STRUCTURED-LOCATION;VALUE=URI:geo:40.443,-79.945;u=10 497 END:VALARM 499 9. Security Considerations 501 VALARMs, if not monitored properly, can be used to "spam" users and/ 502 or leak personal information. For instance, an unwanted audio or 503 display alert could be considered spam. Or an email alert could be 504 used to leak a user's location to a third party or to send 505 unsolicited email to multiple users. Therefore, CalDAV clients and 506 servers that accept iCalendar data from a third party (e.g. via iTIP 507 [RFC5546], a subscription feed, or a shared calendar) SHOULD remove 508 all VALARMs from the data prior to storing in their calendar system. 510 10. Privacy Considerations 512 Proximity VALARMs, if not used carefully, can leak a user's past, 513 present, or future location. For instance, storing an iCalendar 514 resource containing proxmity VALARMs to a shared calendar on CalDAV 515 server can expose to anyone that has access to that calendar the 516 user's intent to leave from or arrive at a particular location at 517 some future time. Furthermore, if a CalDAV client updates the shared 518 iCalendar resource with an ACKNOWLEDGED property when the alarm is 519 triggered, will leak the exact date and time that the user left from 520 or arrived at the location. Therefore, CalDAV clients that implement 521 proximity alarms SHOULD give users the option of storing and/or 522 acknowledging the alarms on the local device only and not storing the 523 alarm and/or acknowledgment on a remote server. 525 11. IANA Considerations 527 11.1. Property Registrations 529 This document defines the following new iCalendar properties to be 530 added to the registry defined in Section 8.2.3 of [RFC5545]: 532 +--------------+---------+----------------------+ 533 | Property | Status | Reference | 534 +--------------+---------+----------------------+ 535 | ACKNOWLEDGED | Current | RFCXXXX, Section 6.1 | 536 | PROXIMITY | Current | RFCXXXX, Section 8.1 | 537 +--------------+---------+----------------------+ 539 11.2. Relationship Types Registry 541 This document defines the following new iCalendar relationship type 542 to be added to the registry defined in Section 8.3.8 of [RFC5545]: 544 +-------------------+---------+----------------------+ 545 | Relationship Type | Status | Reference | 546 +-------------------+---------+----------------------+ 547 | SNOOZE | Current | RFCXXXX, Section 7.1 | 548 +-------------------+---------+----------------------+ 550 11.3. Proximity Value Registry 552 This document creates a new iCalendar registry for values of the 553 "PROXIMITY" property: 555 +------------+---------+----------------------+ 556 | Value | Status | Reference | 557 +------------+---------+----------------------+ 558 | ARRIVE | Current | RFCXXXX, Section 8.1 | 559 | DEPART | Current | RFCXXXX, Section 8.1 | 560 | CONNECT | Current | RFCXXXX, Section 8.1 | 561 | DISCONNECT | Current | RFCXXXX, Section 8.1 | 562 +------------+---------+----------------------+ 564 12. Acknowledgments 566 This specification came about via discussions at the Calendaring and 567 Scheduling Consortium. Also, thanks to the following for providing 568 feedback: Bernard Desruisseaux, Mike Douglass, Jacob Farkas, Jeffrey 569 Harris, and Ciny Joy. 571 13. References 573 13.1. Normative References 575 [I-D.ietf-calext-eventpub-extensions] 576 Douglass, M., "Event Publishing Extensions to iCalendar", 577 draft-ietf-calext-eventpub-extensions-16 (work in 578 progress), October 2020. 580 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 581 Requirement Levels", BCP 14, RFC 2119, 582 DOI 10.17487/RFC2119, March 1997, 583 . 585 [RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault, 586 "Calendaring Extensions to WebDAV (CalDAV)", RFC 4791, 587 DOI 10.17487/RFC4791, March 2007, 588 . 590 [RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and 591 Scheduling Core Object Specification (iCalendar)", 592 RFC 5545, DOI 10.17487/RFC5545, September 2009, 593 . 595 [RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource 596 Identifier for Geographic Locations ('geo' URI)", 597 RFC 5870, DOI 10.17487/RFC5870, June 2010, 598 . 600 [RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986, 601 DOI 10.17487/RFC7986, October 2016, 602 . 604 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 605 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 606 May 2017, . 608 13.2. Informative References 610 [BTcore] Bluetooth Special Interest Group, "Bluetooth Core 611 Specification Version 5.0", December 2016, 612 . 615 [RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent 616 Interoperability Protocol (iTIP)", RFC 5546, 617 DOI 10.17487/RFC5546, December 2009, 618 . 620 13.3. URIs 622 [1] https://tools.ietf.org/html/bcp14 624 Appendix A. Change History (To be removed by RFC Editor before 625 publication) 627 Changes in ietf-02: 629 1. Addressed some WGLC comments from Daniel Migault. 631 Changes in ietf-01: 633 1. Reintroduced the RELATED-TO property for VALARMs and the SNOOZE 634 value for the RELTYPE property parameter. 636 2. Add Privacy Considerations section. 638 Changes in ietf-00: 640 1. Submitted as CALEXT draft. 642 Changes in daboo-05: 644 1. Added Murchison as editor. 646 2. Updated keywords boilerplate. 648 3. Added reference to UID security/privacy recommendations. 650 4. Removed default alarms. 652 5. Removed ALARM-AGENT property. 654 6. Added text about using TRIGGER value in the past in addition to 655 ACTION:NONE to have a default alarm be ignored. 657 7. Removed text about related alarms. 659 8. Removed URL alarm action. 661 9. Added reference to draft-ietf-calext-eventpub-extensions for 662 STRUCTURED-LOCATION. 664 10. Added CONNECT and DISCONNECT PROXIMITY property values. 666 11. Added Security Considerations. 668 12. Editorial fixes. 670 Changes in daboo-04: 672 1. Changed "ID" to "AGENT-ID". 674 2. Add more text on using "ACKNOWLEDGED" property. 676 3. Add "RELATED-TO" as a valid property for VALARMs. 678 4. Add "SNOOZE" relationship type for use with VALARMs. 680 5. State that "TRIGGER" is typically ignored in proximity alarms. 682 6. Added "PROXIMITY" value registry. 684 7. Added a lot more detail on default alarms including new action 685 and property. 687 Changes in daboo-03: none - resubmission of -02 689 Changes in daboo-02: 691 1. Updated to 5545 reference. 693 2. Clarified use of absolute trigger in UTC in snooze alarms 695 3. Snooze alarms should be removed when completed 697 4. Removed status and replaced last-triggered by acknowledged 698 property 700 5. Added location-based trigger 702 6. IANA registry tables added 704 Changes in daboo-01: 706 1. Removed DESCRIPTION as an allowed property in the URI alarm. 708 2. Added statement about what to do when ALARM-AGENT is not present. 710 3. Allow multiple ALARM-AGENT properties to be present. 712 4. Removed SNOOZE-UNTIL - snoozing now accomplished by creating a 713 new VALARM. 715 5. Remove VALARM by reference section. 717 6. Added more detail to CalDAV default alarms. 719 Authors' Addresses 721 Cyrus Daboo 722 Apple Inc. 723 1 Infinite Loop 724 Cupertino, CA 95014 725 USA 727 Email: cyrus@daboo.name 728 URI: http://www.apple.com/ 730 Kenneth Murchison (editor) 731 Fastmail US LLC 732 1429 Walnut St, Suite 1201 733 Philadephia, PA 19102 734 USA 736 Email: murch@fastmailteam.com 737 URI: http://www.fastmail.com/