Non-Gregorian Recurrence Rules in the Internet Calendaring and Scheduling Core Object Specification (iCalendar)
RFC 7529
| Document | Type | RFC - Proposed Standard (May 2015; No errata) | |
|---|---|---|---|
| Authors | Cyrus Daboo , Gregory Yakushev | ||
| Last updated | 2015-10-14 | ||
| Replaces | draft-daboo-icalendar-rscale | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Donald Eastlake | ||
| Shepherd write-up | Show (last changed 2015-02-26) | ||
| IESG | IESG state | RFC 7529 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Barry Leiba | ||
| Send notices to | (None) | ||
| IANA | IANA review state | IANA OK - No Actions Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) C. Daboo
Request for Comments: 7529 Apple Inc.
Updates: 5545, 6321, 7265 G. Yakushev
Category: Standards Track Google Inc.
ISSN: 2070-1721 May 2015
Non-Gregorian Recurrence Rules in the Internet Calendaring and
Scheduling Core Object Specification (iCalendar)
Abstract
This document defines extensions to the Internet Calendaring and
Scheduling Core Object Specification (iCalendar) (RFC 5545) to
support use of non-Gregorian recurrence rules. It also defines how
Calendaring Extensions to WebDAV (CalDAV) (RFC 4791) servers and
clients can be extended to support these new recurrence rules.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7529.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Daboo & Yakushev Standards Track [Page 1]
RFC 7529 iCalendar RSCALE Extension May 2015
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Extended RRULE Property . . . . . . . . . . . . . . . . . . . 6
4.1. Skipping Invalid Dates . . . . . . . . . . . . . . . . . 6
4.2. Handling Leap Months . . . . . . . . . . . . . . . . . . 9
4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Registering Calendar Systems . . . . . . . . . . . . . . . . 13
6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Use with iTIP . . . . . . . . . . . . . . . . . . . . . . . . 14
8. Use with xCal . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Use with jCal . . . . . . . . . . . . . . . . . . . . . . . . 15
10. Use with CalDAV . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. CALDAV:supported-rscale-set Property . . . . . . . . . . 17
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
12.1. Normative References . . . . . . . . . . . . . . . . . . 18
12.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. xCal RELAX NG Schema Update . . . . . . . . . . . . 20
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
The iCalendar [RFC5545] data format is in widespread use to represent
calendar data. iCalendar represents dates and times using the
Gregorian calendar system only. It does provide a way to use non-
Gregorian calendar systems via a "CALSCALE" property, but this has
never been used. However, there is a need to support at least non-
Gregorian recurrence patterns to cover anniversaries, and many local,
religious, or civil holidays based on non-Gregorian dates.
There are several disadvantages to using the existing "CALSCALE"
property in iCalendar for implementing non-Gregorian calendars:
1. The "CALSCALE" property exists in the top-level "VCALENDAR"
objects and thus applies to all components within that object.
In today's multi-cultural society, that restricts the ability to
mix events from different calendar systems within the same
iCalendar object, e.g., it would prevent having both the
Gregorian New Year and Chinese New Year in the same iCalendar
object.
2. Time zone and daylight saving time rules are typically published
using Gregorian calendar dates and rules (e.g., "the 3rd Sunday
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