Internet Calendaring and Scheduling Core Object Specification (iCalendar)

Abstract

This document defines the iCalendar data format for representing and exchanging calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, independent of any particular calendar service or protocol.

Status of This Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the “Internet Official Protocol Standards” (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

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Table of Contents

• 1. Introduction
• 2. Basic Grammar and Conventions
  • 2.1. Formatting Conventions
  • 2.2. Related Memos
• 3. iCalendar Object Specification
  • 3.1 Content Lines
    • 3.1.1. List and Field Separators
    • 3.1.2. Multiple Values
    • 3.1.3. Binary Content
    • 3.1.4. Character Set
  • 3.2. Property Parameters
    • 3.2.1 Alternate Text Representation
    • 3.2.2. Common Name
    • 3.2.3. Calendar User Type
    • 3.2.4. Delegators
    • 3.2.5. Delegatees

  3.2.  Property Parameters . . . . . . . . . . . . . . . . . . .  12
    3.2.1.  Alternate Text Representation . . . . . . . . . . . .  13
    3.2.2.  Common Name . . . . . . . . . . . . . . . . . . . . .  15
    3.2.3.  Calendar User Type  . . . . . . . . . . . . . . . . .  15
    3.2.4.  Delegators  . . . . . . . . . . . . . . . . . . . . .  16
    3.2.5.  Delegatees  . . . . . . . . . . . . . . . . . . . . .  16
    3.2.6.  Directory Entry Reference . . . . . . . . . . . . . .  17
    3.2.7.  Inline Encoding . . . . . . . . . . . . . . . . . . .  17
    3.2.8.  Format Type . . . . . . . . . . . . . . . . . . . . .  18
    3.2.9.  Free/Busy Time Type . . . . . . . . . . . . . . . . .  19
    3.2.10. Language  . . . . . . . . . . . . . . . . . . . . . .  20
    3.2.11. Group or List Membership  . . . . . . . . . . . . . .  20
    3.2.12. Participation Status  . . . . . . . . . . . . . . . .  21
    3.2.13. Recurrence Identifier Range . . . . . . . . . . . . .  22
    3.2.14. Alarm Trigger Relationship  . . . . . . . . . . . . .  23
    3.2.15. Relationship Type . . . . . . . . . . . . . . . . . .  24
    3.2.16. Participation Role  . . . . . . . . . . . . . . . . .  25
    3.2.17. RSVP Expectation  . . . . . . . . . . . . . . . . . .  25
    3.2.18. Sent By . . . . . . . . . . . . . . . . . . . . . . .  26
    3.2.19. Time Zone Identifier  . . . . . . . . . . . . . . . .  26
    3.2.20. Value Data Types  . . . . . . . . . . . . . . . . . .  28
  3.3.  Property Value Data Types . . . . . . . . . . . . . . . .  29
    3.3.1.  Binary  . . . . . . . . . . . . . . . . . . . . . . .  29
    3.3.2.  Boolean . . . . . . . . . . . . . . . . . . . . . . .  30
    3.3.3.  Calendar User Address . . . . . . . . . . . . . . . .  30
    3.3.4.  Date  . . . . . . . . . . . . . . . . . . . . . . . .  31
    3.3.5.  Date-Time . . . . . . . . . . . . . . . . . . . . . .  31
    3.3.6.  Duration  . . . . . . . . . . . . . . . . . . . . . .  34
    3.3.7.  Float . . . . . . . . . . . . . . . . . . . . . . . .  35
    3.3.8.  Integer . . . . . . . . . . . . . . . . . . . . . . .  35
    3.3.9.  Period of Time  . . . . . . . . . . . . . . . . . . .  36
    3.3.10. Recurrence Rule . . . . . . . . . . . . . . . . . . .  37
    3.3.11. Text  . . . . . . . . . . . . . . . . . . . . . . . .  45
    3.3.12. Time  . . . . . . . . . . . . . . . . . . . . . . . .  46
    3.3.13. URI . . . . . . . . . . . . . . . . . . . . . . . . .  48
    3.3.14. UTC Offset  . . . . . . . . . . . . . . . . . . . . .  49
  3.4.  iCalendar Object  . . . . . . . . . . . . . . . . . . . .  49
  3.5.  Property  . . . . . . . . . . . . . . . . . . . . . . . .  50
  3.6.  Calendar Components . . . . . . . . . . . . . . . . . . .  50
    3.6.1.  Event Component . . . . . . . . . . . . . . . . . . .  52
    3.6.2.  To-Do Component . . . . . . . . . . . . . . . . . . .  56
    3.6.3.  Journal Component . . . . . . . . . . . . . . . . . .  58
    3.6.4.  Free/Busy Component . . . . . . . . . . . . . . . . .  60
    3.6.5.  Time Zone Component . . . . . . . . . . . . . . . . .  63
    3.6.6.  Alarm Component . . . . . . . . . . . . . . . . . . .  72
  3.7.  Calendar Properties . . . . . . . . . . . . . . . . . . .  77
    3.7.1.  Calendar Scale  . . . . . . . . . . . . . . . . . . .  77
    3.7.2.  Method  . . . . . . . . . . . . . . . . . . . . . . .  78
    3.7.3.  Product Identifier  . . . . . . . . . . . . . . . . .  79
    3.7.4.  Version . . . . . . . . . . . . . . . . . . . . . . .  80
  3.8.  Component Properties  . . . . . . . . . . . . . . . . . .  81
    3.8.1.  Descriptive Component Properties  . . . . . . . . . .  81
      3.8.1.1.  Attachment  . . . . . . . . . . . . . . . . . . .  81
      3.8.1.2.  Categories  . . . . . . . . . . . . . . . . . . .  82
      3.8.1.3.  Classification  . . . . . . . . . . . . . . . . .  83
      3.8.1.4.  Comment . . . . . . . . . . . . . . . . . . . . .  84
      3.8.1.5.  Description . . . . . . . . . . . . . . . . . . .  85
      3.8.1.6.  Geographic Position . . . . . . . . . . . . . . .  87
      3.8.1.7.  Location  . . . . . . . . . . . . . . . . . . . .  88
      3.8.1.8.  Percent Complete  . . . . . . . . . . . . . . . .  89
      3.8.1.9.  Priority  . . . . . . . . . . . . . . . . . . . .  90
      3.8.1.10. Resources . . . . . . . . . . . . . . . . . . . .  92
      3.8.1.11. Status  . . . . . . . . . . . . . . . . . . . . .  93
      3.8.1.12. Summary . . . . . . . . . . . . . . . . . . . . .  94
    3.8.2.  Date and Time Component Properties  . . . . . . . . .  95
      3.8.2.1.  Date-Time Completed . . . . . . . . . . . . . . .  95
      3.8.2.2.  Date-Time End . . . . . . . . . . . . . . . . . .  96
      3.8.2.3.  Date-Time Due . . . . . . . . . . . . . . . . . .  97
      3.8.2.4.  Date-Time Start . . . . . . . . . . . . . . . . .  99
      3.8.2.5.  Duration  . . . . . . . . . . . . . . . . . . . . 100
      3.8.2.6.  Free/Busy Time  . . . . . . . . . . . . . . . . . 101
      3.8.2.7.  Time Transparency . . . . . . . . . . . . . . . . 102
    3.8.3.  Time Zone Component Properties  . . . . . . . . . . . 103
      3.8.3.1.  Time Zone Identifier  . . . . . . . . . . . . . . 103
      3.8.3.2.  Time Zone Name  . . . . . . . . . . . . . . . . . 105
      3.8.3.3.  Time Zone Offset From . . . . . . . . . . . . . . 106
      3.8.3.4.  Time Zone Offset To . . . . . . . . . . . . . . . 106
      3.8.3.5.  Time Zone URL . . . . . . . . . . . . . . . . . . 107
    3.8.4.  Relationship Component Properties . . . . . . . . . . 108
      3.8.4.1.  Attendee  . . . . . . . . . . . . . . . . . . . . 108
      3.8.4.2.  Contact . . . . . . . . . . . . . . . . . . . . . 111
      3.8.4.3.  Organizer . . . . . . . . . . . . . . . . . . . . 113
      3.8.4.4.  Recurrence ID . . . . . . . . . . . . . . . . . . 114
      3.8.4.5.  Related To  . . . . . . . . . . . . . . . . . . . 117
      3.8.4.6.  Uniform Resource Locator  . . . . . . . . . . . . 118
      3.8.4.7.  Unique Identifier . . . . . . . . . . . . . . . . 119
    3.8.5.  Recurrence Component Properties . . . . . . . . . . . 120
      3.8.5.1.  Exception Date-Times  . . . . . . . . . . . . . . 120
      3.8.5.2.  Recurrence Date-Times . . . . . . . . . . . . . . 122
      3.8.5.3.  Recurrence Rule . . . . . . . . . . . . . . . . . 124
    3.8.6.  Alarm Component Properties  . . . . . . . . . . . . . 134
      3.8.6.1.  Action  . . . . . . . . . . . . . . . . . . . . . 134
      3.8.6.2.  Repeat Count  . . . . . . . . . . . . . . . . . . 135
      3.8.6.3.  Trigger . . . . . . . . . . . . . . . . . . . . . 135
    3.8.7.  Change Management Component Properties  . . . . . . . 138
      3.8.7.1.  Date-Time Created . . . . . . . . . . . . . . . . 138
      3.8.7.2.  Date-Time Stamp . . . . . . . . . . . . . . . . . 139
      3.8.7.3.  Last Modified . . . . . . . . . . . . . . . . . . 140
      3.8.7.4.  Sequence Number . . . . . . . . . . . . . . . . . 141
    3.8.8.  Miscellaneous Component Properties  . . . . . . . . . 142
      3.8.8.1.  IANA Properties . . . . . . . . . . . . . . . . . 142
      3.8.8.2.  Non-Standard Properties . . . . . . . . . . . . . 142
      3.8.8.3.  Request Status  . . . . . . . . . . . . . . . . . 144
4.  iCalendar Object Examples . . . . . . . . . . . . . . . . . . 146
5.  Recommended Practices . . . . . . . . . . . . . . . . . . . . 150
6.  Internationalization Considerations . . . . . . . . . . . . . 151
7.  Security Considerations . . . . . . . . . . . . . . . . . . . 151
8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . 151
  8.1.  iCalendar Media Type Registration . . . . . . . . . . . . 151
  8.2.  New iCalendar Elements Registration . . . . . . . . . . . 155
    8.2.1.  iCalendar Elements Registration Procedure . . . . . . 155
    8.2.2.  Registration Template for Components  . . . . . . . . 155
    8.2.3.  Registration Template for Properties  . . . . . . . . 156
    8.2.4.  Registration Template for Parameters  . . . . . . . . 156
    8.2.5.  Registration Template for Value Data Types  . . . . . 157
    8.2.6.  Registration Template for Values  . . . . . . . . . . 157
  8.3.  Initial iCalendar Elements Registries . . . . . . . . . . 158
    8.3.1.  Components Registry . . . . . . . . . . . . . . . . . 158
    8.3.2.  Properties Registry . . . . . . . . . . . . . . . . . 158
    8.3.3.  Parameters Registry . . . . . . . . . . . . . . . . . 161
    8.3.4.  Value Data Types Registry . . . . . . . . . . . . . . 162
    8.3.5.  Calendar User Types Registry  . . . . . . . . . . . . 162
    8.3.6.  Free/Busy Time Types Registry . . . . . . . . . . . . 163
    8.3.7.  Participation Statuses Registry . . . . . . . . . . . 163
    8.3.8.  Relationship Types Registry . . . . . . . . . . . . . 164
    8.3.9.  Participation Roles Registry  . . . . . . . . . . . . 164
    8.3.10. Actions Registry  . . . . . . . . . . . . . . . . . . 165
    8.3.11. Classifications Registry  . . . . . . . . . . . . . . 165
    8.3.12. Methods Registry  . . . . . . . . . . . . . . . . . . 165
9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 165
10. References  . . . . . . . . . . . . . . . . . . . . . . . . . 166
  10.1. Normative References  . . . . . . . . . . . . . . . . . . 166
  10.2. Informative References  . . . . . . . . . . . . . . . . . 167
Appendix A.  Differences from RFC 2445  . . . . . . . . . . . . . 169
  A.1.  New Restrictions  . . . . . . . . . . . . . . . . . . . . 169
  A.2.  Restrictions Removed  . . . . . . . . . . . . . . . . . . 169
  A.3.  Deprecated Features . . . . . . . . . . . . . . . . . . . 169