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Daboo 3 Internet-Draft Apple 4 Updates: 5545 (if approved) K. Murchison, Ed. 5 Intended status: Standards Track FastMail 6 Expires: July 20, 2020 January 17, 2020 8 VALARM Extensions for iCalendar 9 draft-ietf-calext-valarm-extensions-01 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 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at https://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on July 20, 2020. 34 Copyright Notice 36 Copyright (c) 2020 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (https://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 53 3. Extensible syntax for VALARM . . . . . . . . . . . . . . . . 3 54 4. Alarm Unique Identifier . . . . . . . . . . . . . . . . . . . 5 55 5. Alarm Related To . . . . . . . . . . . . . . . . . . . . . . 5 56 6. Alarm Acknowledgement . . . . . . . . . . . . . . . . . . . . 6 57 6.1. Acknowledged Property . . . . . . . . . . . . . . . . . . 7 58 7. Snoozing Alarms . . . . . . . . . . . . . . . . . . . . . . . 8 59 7.1. Relationship Type Property Parameter . . . . . . . . . . 8 60 8. Alarm Proximity Trigger . . . . . . . . . . . . . . . . . . . 9 61 8.1. Proximity Property . . . . . . . . . . . . . . . . . . . 10 62 8.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 11 63 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 64 10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 11 65 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 66 11.1. Property Registrations . . . . . . . . . . . . . . . . . 12 67 11.2. Relationship Types Registry . . . . . . . . . . . . . . 12 68 11.3. Proximity Value Registry . . . . . . . . . . . . . . . . 12 69 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 70 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 71 13.1. Normative References . . . . . . . . . . . . . . . . . . 13 72 13.2. Informative References . . . . . . . . . . . . . . . . . 13 73 13.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 14 74 Appendix A. Change History (To be removed by RFC Editor before 75 publication) . . . . . . . . . . . . . . . . . . . . 14 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 78 1. Introduction 80 The iCalendar [RFC5545] specification defines a set of components 81 used to describe calendar data. One of those is the "VALARM" 82 component which appears as a sub-component of "VEVENT" and "VTODO" 83 components. The "VALARM" component is used to specify a reminder for 84 an event or task. Different alarm actions are possible, as are 85 different ways to specify how the alarm is triggered. 87 As iCalendar has become more widely used and as client-server 88 protocols such as CalDAV [RFC4791] have become more popular, several 89 issues with "VALARM" components have arisen. Most of these relate to 90 the need to extend the existing "VALARM" component with new 91 properties and behaviors to allow clients and servers to accomplish 92 specific tasks in an interoperable manner. For example, clients 93 typically need a way to specify that an alarm has been dismissed by a 94 calendar user, or has been "snoozed" by a set amount of time. To 95 date, this has been done through the use of custom "X-" properties 96 specific to each client implementation, leading to poor 97 interoperability. 99 This specification defines a set of extensions to "VALARM" components 100 to cover common requirements for alarms not currently addressed in 101 iCalendar. Each extension is defined in a separate section below. 102 For the most part, each extension can be supported independently of 103 the others, though in some cases one extension will require another. 104 In addition, this specification describes mechanisms by which clients 105 can interoperably implement common features such as "snoozing". 107 2. Conventions Used in This Document 109 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 110 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 111 "OPTIONAL" in this document are to be interpreted as described in BCP 112 14 [1] [RFC2119] [RFC8174] when, and only when, they appear in all 113 capitals, as shown here. 115 When XML element types in the namespaces "DAV:" and 116 "urn:ietf:params:xml:ns:caldav" are referenced in this document 117 outside of the context of an XML fragment, the string "DAV:" and 118 "CALDAV:" will be prefixed to the element type names respectively. 120 3. Extensible syntax for VALARM 122 Section 3.6.6 of [RFC5545] defines the syntax for "VALARM" components 123 and properties within them. However, as written, it is hard to 124 extend this by adding, e.g., a new property common to all types of 125 alarm. Since many of the extensions defined in this document need to 126 extend the base syntax, an alternative form for the base syntax is 127 defined here, with the goal of simplifying specification of the 128 extensions. 130 A "VALARM" calendar component is re-defined by the following 131 notation: 133 alarmcext = "BEGIN" ":" "VALARM" CRLF 134 alarmprop 135 "END" ":" "VALARM" CRLF 137 alarmprop = *( 139 ; the following are REQUIRED, 140 ; but MUST NOT occur more than once 142 action / trigger / 143 ; one set of action properties MUST be 144 ; present and MUST match the action specified 145 ; in the ACTION property 147 actionprops / 149 ; the following is OPTIONAL, 150 ; and MAY occur more than once 152 x-prop / iana-prop 154 ) 156 actionprops = audiopropext / disppropext / emailpropext 158 audiopropext = *( 160 ; 'duration' and 'repeat' are both OPTIONAL, 161 ; and MUST NOT occur more than once each, 162 ; but if one occurs, so MUST the other 164 duration / repeat / 166 ; the following is OPTIONAL, 167 ; but MUST NOT occur more than once 169 attach 171 ) 173 disppropext = *( 175 ; the following are REQUIRED, 176 ; but MUST NOT occur more than once 178 description / 180 ; 'duration' and 'repeat' are both OPTIONAL, 181 ; and MUST NOT occur more than once each, 182 ; but if one occurs, so MUST the other 184 duration / repeat 186 ) 188 emailpropext = *( 190 ; the following are all REQUIRED, 191 ; but MUST NOT occur more than once 193 description / summary / 195 ; the following is REQUIRED, 196 ; and MAY occur more than once 198 attendee / 200 ; 'duration' and 'repeat' are both OPTIONAL, 201 ; and MUST NOT occur more than once each, 202 ; but if one occurs, so MUST the other 204 duration / repeat 206 ) 208 4. Alarm Unique Identifier 210 This extension adds a "UID" property to "VALARM" components to allow 211 a unique identifier to specified. The value of this property can 212 then be used to refer uniquely to the "VALARM" component. 214 The "UID" property defined here follows the definition in 215 Section 3.8.4.7 of [RFC5545] with the security and privacy updates in 216 Section 5.3 of [RFC7986]. In particular it MUST be a globally unique 217 identifier that does not contain any security- or privacy-sensitive 218 information. 220 The "VALARM" component defined in Section 3 is extended here as: 222 alarmprop /= *( 224 ; the following is OPTIONAL, 225 ; but MUST NOT occur more than once 227 uid 229 ) 231 5. Alarm Related To 233 It is often convenient to relate one or more "VALARM" components to 234 other "VALARM" components (e.g., see Section 7). This can be 235 accomplished if the "VALARM" components each have their own "UID" 236 property (as per Section 4). 238 This specification updates the usage of the "RELATED-TO" property 239 defined in Section 3.8.4.5 of [RFC5545] to enable its use with 240 "VALARM" components. Specific types of relationships between 241 "VALARM" components can be identified by registering new values for 242 the "RELTYPE" property parameter defined in Section 3.2.15 of 243 [RFC5545]. 245 The "VALARM" component defined in Section 3 is extended here as: 247 alarmprop /= *( 249 ; the following is OPTIONAL, 250 ; but MAY occur more than once 252 related 254 ) 256 6. Alarm Acknowledgement 258 There is currently no way for a "VALARM" component to indicate 259 whether it has been triggered and acknowledged. With the advent of a 260 standard client/server protocol for calendaring and scheduling data 261 ([RFC4791]) it is quite possible for an event with an alarm to exist 262 on multiple clients in addition to the server. If each of those is 263 responsible for performing the action when an alarm triggers, then 264 multiple "alerts" are generated by different devices. In such a 265 situation, a calendar user would like to be able to "dismiss" the 266 alarm on one device and have it automatically dismissed on the others 267 too. 269 Also, with recurring events that have alarms, it is important to know 270 when the last alarm in the recurring set was acknowledged, so that 271 the client can determine whether past alarms have been missed. 273 To address these needs, this specification adds an "ACKNOWLEDGED" 274 property to "VALARM" components to indicate when the alarm was last 275 sent or acknowledged. This is defined by the syntax below. 277 alarmprop /= *( 279 ; the following is OPTIONAL, 280 ; but MUST NOT occur more than once 282 acknowledged 284 ) 286 6.1. Acknowledged Property 288 Property Name: ACKNOWLEDGED 290 Purpose: This property specifies the UTC date and time at which the 291 corresponding alarm was last sent or acknowledged. 293 Value Type: DATE-TIME 295 Property Parameters: IANA and non-standard property parameters can 296 be specified on this property. 298 Conformance: This property can be specified within "VALARM" calendar 299 components. 301 Description: This property is used to specify when an alarm was last 302 sent or acknowledged. This allows clients to determine when a 303 pending alarm has been acknowledged by a calendar user so that any 304 alerts can be dismissed across multiple devices. It also allows 305 clients to track repeating alarms or alarms on recurring events or 306 to-dos to ensure that the right number of missed alarms can be 307 tracked. 309 Clients SHOULD set this property to the current date-time value in 310 UTC when a calendar user acknowledges a pending alarm. Certain 311 kinds of alarm may not provide feedback as to when the calendar 312 user sees them, for example email based alerts. For those kinds 313 of alarms, the client SHOULD set this property when the alarm is 314 triggered and the action successfully carried out. 316 When an alarm is triggered on a client, clients can check to see 317 if an "ACKNOWLEDGED" property is present. If it is, and the value 318 of that property is greater than or equal to the computed trigger 319 time for the alarm, then the client SHOULD NOT trigger the alarm. 320 Similarly, if an alarm has been triggered and an "alert" presented 321 to a calendar user, clients can monitor the iCalendar data to 322 determine whether an "ACKNOWLEDGED" property is added or changed 323 in the alarm component. If the value of any "ACKNOWLEDGED" 324 property in the alarm changes and is greater than or equal to the 325 trigger time of the alarm, then clients SHOULD dismiss or cancel 326 any "alert" presented to the calendar user. 328 Format Definition: This property is defined by the following 329 notation: 331 acknowledged = "ACKNOWLEDGED" acknowledgedparam ":" datetime CRLF 333 acknowledgedparam = *( 335 ; the following is OPTIONAL, 336 ; and MAY occur more than once 338 (";" other-param) 340 ) 342 Example: The following is an example of this property: 344 ACKNOWLEDGED:20090604T084500Z 346 7. Snoozing Alarms 348 Users often want to "snooze" an alarm, and this specification defines 349 a standard approach to accomplish that. 351 To "snooze" an alarm, clients create a new "VALARM" component within 352 the parent component of the "VALARM" that was triggered and is being 353 "snoozed" (i.e., as a "sibling" component of the "VALARM" being 354 snoozed). The new "VALARM" MUST be set to trigger at the user's 355 chosen "snooze" interval after the original alarm triggered. Clients 356 SHOULD use an absolute "TRIGGER" property with a "DATE-TIME" value 357 specified in UTC. 359 Clients SHOULD add a "RELATED-TO" property to the new "VALARM" 360 component with a value set to the "UID" property value of the 361 "VALARM" component being snoozed. If the "VALARM" component being 362 snoozed does not already have a "UID" property, the client SHOULD add 363 one. The "RELATED-TO" property added to the new "VALARM" component 364 SHOULD include a "RELTYPE" property parameter with a value set to 365 "SNOOZE". 367 When the "snooze" alarm is triggered and dismissed the client SHOULD 368 remove the corresponding "VALARM" component, or set the 369 "ACKNOWLEDGED" property (see Section 6.1). Alternatively, if the 370 "snooze" alarm is itself "snoozed", the client SHOULD remove the 371 original "snooze" alarm and create a new one, with the appropriate 372 trigger time and relationship set. 374 7.1. Relationship Type Property Parameter 376 This specification adds the "SNOOZE" relationship type for use with 377 the "RELTYPE" property defined in Section 3.2.15 of [RFC5545]. This 378 is used to relate a "snoozed" "VALARM" component to the original 379 alarm that the "snooze" was generated for. 381 8. Alarm Proximity Trigger 383 VALARMs are currently triggered when a specific date-time is reached. 384 It is also desirable to be able to trigger alarms based on location, 385 e.g. when arriving at or departing from a particular location. 387 This specification adds the following properties to "VALARM" 388 components to indicate when an alarm can be triggered based on 389 location. 391 "PROXIMITY" - indicates that a location based trigger is to be 392 used and which direction of motion is used for the trigger 394 "STRUCTURED-LOCATION" [I-D.ietf-calext-eventpub-extensions] - used 395 to indicate the actual location to trigger off, specified using a 396 geo: URI [RFC5870] which allows for two or three coordinate values 397 with an optional uncertainty 399 alarmprop /= *( 401 ; the following is OPTIONAL, 402 ; but MUST NOT occur more than once 404 proximity / 406 ; the following is OPTIONAL, 407 ; and MAY occur more than once, but only 408 ; when a PROXIMITY property is also present 410 structured-location 412 ) 414 Typically, when a "PROXIMITY" property is used there is no need to 415 specify a time-based trigger using the "TRIGGER" property. However, 416 since "TRIGGER" is defined as a required property for a "VALARM" 417 component, for backwards compatibility it has to be present, but 418 ignored. To indicate a "TRIGGER" that is to be ignored, clients 419 SHOULD use a value a long time in the past. A value of 420 "19760401T005545Z" has been commonly used for this purpose. 422 8.1. Proximity Property 424 Property Name: PROXIMITY 426 Purpose: This property indicates that a location based trigger is 427 applied to an alarm. 429 Value Type: TEXT 431 Property Parameters: IANA and non-standard property parameters can 432 be specified on this property. 434 Conformance: This property can be specified within "VALARM" calendar 435 components. 437 Description: This property is used to indicate that an alarm has a 438 location-based trigger. Its value identifies the direction of 439 motion used to trigger the alarm. One or more location values are 440 set using "STRUCTURED-LOCATION" properties. 442 When the property value is set to "ARRIVE", the alarm is triggered 443 when the calendar user agent arrives in the vicinity of any of the 444 specified locations. When set to "DEPART", the alarm is triggered 445 when the calendar user agent departs from the vicinity of any 446 specified locations. 448 When the property value is set to "CONNECT", the alarm is 449 triggered when the calendar user agent connects to a Bluetooth(R) 450 [BTcore]-enabled automobile. When set to "DISCONNECT", the alarm 451 is triggered when the calendar user agent disconnects from a 452 Bluetooth(R)-enabled automobile. 454 Format Definition: This property is defined by the following 455 notation: 457 proximity = "PROXIMITY" proximityparam ":" proximityvalue CRLF 459 proximityparam = *( 461 ; the following is OPTIONAL, 462 ; and MAY occur more than once 464 (";" other-param) 466 ) 468 proximityvalue = "ARRIVE" / "DEPART" / 469 "CONNECT" / "DISCONNECT" / iana-token / x-name 471 Example: The following is an example of this property: 473 PROXIMITY:ARRIVE 475 8.2. Example 477 The following example shows a "VALARM" component with a proximity 478 trigger set to trigger when the device running the calendar user 479 agent leaves the vicinity defined by the structured location 480 property. Note use of the "u=" parameter with the "geo" URI to 481 define the precision of the location determination. 483 BEGIN:VALARM 484 UID:77D80D14-906B-4257-963F-85B1E734DBB6 485 TRIGGER;VALUE=DATE-TIME:19760401T005545Z 486 ACTION:DISPLAY 487 DESCRIPTION:Remember to buy milk 488 TRIGGER;VALUE=DATE-TIME:19760401T005545Z 489 PROXIMITY:DEPART 490 STRUCTURED-LOCATION;VALUE=URI:geo:40.443,-79.945;u=10 491 END:VALARM 493 9. Security Considerations 495 VALARMs, if not monitored properly, can be used to "spam" users and/ 496 or leak personal information. For instance, an unwanted audio or 497 display alert could be considered spam. Or an email alert could be 498 used to leak a user's location to a third party or to send 499 unsolicited email to multiple users. Therefore, CalDAV clients and 500 servers that accept iCalendar data from a third party (e.g. via iTIP 501 [RFC5546], a subscription feed, or a shared calendar) SHOULD remove 502 all VALARMs from the data prior to storing in their calendar system. 504 10. Privacy Considerations 506 Proximity VALARMs, if not used carefully, can leak a user's past, 507 present, or future location. For instance, storing an iCalendar 508 resource containing proxmity VALARMs to a shared calendar on CalDAV 509 server can expose to anyone that has access to that calendar the 510 user's intent to leave from or arrive at a particular location at 511 some future time. Furthermore, if a CalDAV client updates the shared 512 iCalendar resource with an ACKNOWLEDGED property when the alarm is 513 triggered, will leak the exact date and time that the user left from 514 or arrived at the location. Therefore, CalDAV clients that implement 515 proximity alarms SHOULD give users the option of storing and/or 516 acknowledging the alarms on the local device only and not storing the 517 alarm and/or acknowledgment on a remote server. 519 11. IANA Considerations 521 11.1. Property Registrations 523 This document defines the following new iCalendar properties to be 524 added to the registry defined in Section 8.2.3 of [RFC5545]: 526 +--------------+---------+----------------------+ 527 | Property | Status | Reference | 528 +--------------+---------+----------------------+ 529 | ACKNOWLEDGED | Current | RFCXXXX, Section 6.1 | 530 | PROXIMITY | Current | RFCXXXX, Section 8.1 | 531 +--------------+---------+----------------------+ 533 11.2. Relationship Types Registry 535 This document defines the following new iCalendar relationship type 536 to be added to the registry defined in Section 8.3.8 of [RFC5545]: 538 +-------------------+---------+----------------------+ 539 | Relationship Type | Status | Reference | 540 +-------------------+---------+----------------------+ 541 | SNOOZE | Current | RFCXXXX, Section 7.1 | 542 +-------------------+---------+----------------------+ 544 11.3. Proximity Value Registry 546 This document creates a new iCalendar registry for values of the 547 "PROXIMITY" property: 549 +------------+---------+----------------------+ 550 | Value | Status | Reference | 551 +------------+---------+----------------------+ 552 | ARRIVE | Current | RFCXXXX, Section 8.1 | 553 | DEPART | Current | RFCXXXX, Section 8.1 | 554 | CONNECT | Current | RFCXXXX, Section 8.1 | 555 | DISCONNECT | Current | RFCXXXX, Section 8.1 | 556 +------------+---------+----------------------+ 558 12. Acknowledgments 560 This specification came about via discussions at the Calendaring and 561 Scheduling Consortium. Also, thanks to the following for providing 562 feedback: Bernard Desruisseaux, Mike Douglass, Jacob Farkas, Jeffrey 563 Harris, and Ciny Joy. 565 13. References 567 13.1. Normative References 569 [I-D.ietf-calext-eventpub-extensions] 570 Douglass, M., "Event Publishing Extensions to iCalendar", 571 draft-ietf-calext-eventpub-extensions-15 (work in 572 progress), October 2019. 574 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 575 Requirement Levels", BCP 14, RFC 2119, 576 DOI 10.17487/RFC2119, March 1997, 577 . 579 [RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault, 580 "Calendaring Extensions to WebDAV (CalDAV)", RFC 4791, 581 DOI 10.17487/RFC4791, March 2007, 582 . 584 [RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and 585 Scheduling Core Object Specification (iCalendar)", 586 RFC 5545, DOI 10.17487/RFC5545, September 2009, 587 . 589 [RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource 590 Identifier for Geographic Locations ('geo' URI)", 591 RFC 5870, DOI 10.17487/RFC5870, June 2010, 592 . 594 [RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986, 595 DOI 10.17487/RFC7986, October 2016, 596 . 598 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 599 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 600 May 2017, . 602 13.2. Informative References 604 [BTcore] Bluetooth Special Interest Group, "Bluetooth Core 605 Specification Version 5.0", December 2016, 606 . 609 [RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent 610 Interoperability Protocol (iTIP)", RFC 5546, 611 DOI 10.17487/RFC5546, December 2009, 612 . 614 13.3. URIs 616 [1] https://tools.ietf.org/html/bcp14 618 Appendix A. Change History (To be removed by RFC Editor before 619 publication) 621 Changes in ietf-01: 623 1. Reintroduced the RELATED-TO property for VALARMs and the SNOOZE 624 value for the RELTYPE property parameter. 626 2. Add Privacy Considerations section. 628 Changes in ietf-00: 630 1. Submitted as CALEXT draft. 632 Changes in daboo-05: 634 1. Added Murchison as editor. 636 2. Updated keywords boilerplate. 638 3. Added reference to UID security/privacy recommendations. 640 4. Removed default alarms. 642 5. Removed ALARM-AGENT property. 644 6. Added text about using TRIGGER value in the past in addition to 645 ACTION:NONE to have a default alarm be ignored. 647 7. Removed text about related alarms. 649 8. Removed URL alarm action. 651 9. Added reference to draft-ietf-calext-eventpub-extensions for 652 STRUCTURED-LOCATION. 654 10. Added CONNECT and DISCONNECT PROXIMITY property values. 656 11. Added Security Considerations. 658 12. Editorial fixes. 660 Changes in daboo-04: 662 1. Changed "ID" to "AGENT-ID". 664 2. Add more text on using "ACKNOWLEDGED" property. 666 3. Add "RELATED-TO" as a valid property for VALARMs. 668 4. Add "SNOOZE" relationship type for use with VALARMs. 670 5. State that "TRIGGER" is typically ignored in proximity alarms. 672 6. Added "PROXIMITY" value registry. 674 7. Added a lot more detail on default alarms including new action 675 and property. 677 Changes in daboo-03: none - resubmission of -02 679 Changes in daboo-02: 681 1. Updated to 5545 reference. 683 2. Clarified use of absolute trigger in UTC in snooze alarms 685 3. Snooze alarms should be removed when completed 687 4. Removed status and replaced last-triggered by acknowledged 688 property 690 5. Added location-based trigger 692 6. IANA registry tables added 694 Changes in daboo-01: 696 1. Removed DESCRIPTION as an allowed property in the URI alarm. 698 2. Added statement about what to do when ALARM-AGENT is not present. 700 3. Allow multiple ALARM-AGENT properties to be present. 702 4. Removed SNOOZE-UNTIL - snoozing now accomplished by creating a 703 new VALARM. 705 5. Remove VALARM by reference section. 707 6. Added more detail to CalDAV default alarms. 709 Authors' Addresses 711 Cyrus Daboo 712 Apple Inc. 713 1 Infinite Loop 714 Cupertino, CA 95014 715 USA 717 Email: cyrus@daboo.name 718 URI: http://www.apple.com/ 720 Kenneth Murchison (editor) 721 FastMail US LLC 722 1429 Walnut St, Suite 1201 723 Philadephia, PA 19102 724 USA 726 Email: murch@fastmailteam.com 727 URI: http://www.fastmail.com/