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Calendaring Extensions

Document Charter Calendaring Extensions WG (calext)
Title Calendaring Extensions
Last updated 2022-03-02
State Approved
WG State Active
IESG Responsible AD Francesca Palombini
Charter edit AD Francesca Palombini
Send notices to (None)


The CALEXT working group is chartered to maintain and extend the specifications for formats and protocols related to calendaring and contacts within the IETF, starting from the basis of:

and the many existing extensions and companion documents to these.

This working group is envisaged to be long-running, and deal with a steady flow of changes. Experience has shown that these specifications are still seeing significant need for updates, as new use-cases are identified and user requirements change.

This working group will do the following:

  • maintain existing standards and proposed standards, processing errata and refreshing them as required

  • evaluate and develop extensions to the existing standards to provide for new use-cases where there is demand

  • generate documents describing existing vendor extensions which are in common usage, and likely to be encountered in the wild.

The working group will work under the following parameters:

  • The extensions developed are expected to be backwards-compatible with the existing standards. Incompatibilities must be identified, minimized, and justified.

  • Any extensions to icalendar or jscalendar must include a representation in both formats, and define a robust mapping between them.

  • Any extensions to vcard or jscontact must include a representation in both formats, and define a robust mapping between them.

  • All calendar extensions must examine their impact on the iTIP protocol (RFC 5546), and define any necessary extensions to iTIP to accommodate such impact.

The working group will maintain relationships with other working groups:

  • HTTPBIS and HTTPAPI: when extending the CalDAV or CardDAV protocols to ensure that changes are consistent with good http practices.

  • JMAP: when making updates to JSCalendar and JSContact to ensure that the changes are compatible with the JMAP methods for managing data in these formats.

  • EXTRA, DMARC and EMAILCORE: for changes related to iTIP delivery via email.

  • TZDIST and SEDATE for date, time, and timezone related issues.

  • Other IETF working groups as appropriate, when their work interacts with ours.

  • Other standards organisations like CalConnect and M3AAWG that are doing work in the same fields.

The following are out of scope for the working group:

  • Any attempt to develop non-Gregorian calendar systems/calculations.

  • Work which is in scope for any other ART area working group, and better suited to that group.

  • Work which is unrelated to anything that this group is currently maintaining.