Calendaring Extensions (calext)

WG Name Calendaring Extensions
Acronym calext
Area Applications and Real-Time Area (art)
State Active
Charter charter-ietf-calext-01 Approved
Dependencies Document dependency graph (SVG)
Additional URLs
- Wiki
- Issue tracker
Personnel Chairs Bron Gondwana
Daniel Migault
Area Director Barry Leiba
Mailing list Address
To subscribe
Jabber chat Room address

Charter for Working Group

The Calendaring Extensions working group is chartered to develop
extensions to the iCalendar (RFC 5545), iTIP (RFC 5546), and
CalDAV (RFC 4791) standards.

This working group will do the following:

- Develop an extension to iCalendar to support non-Gregorian recurrence
rules, without the need to support new calendar scale values in
iCalendar as a whole. This will allow for easy implementation of the
primary use case for non-Gregorian support in calendar systems, without
the need for significant changes to the iCalendar format. The
non-Gregorian calendar system should be based on the International
Components for Unicode work by the Unicode Consortium

- Develop an extension to iCalendar to support a new component type that
allows users to express arbitrary, possibly repeating, periods of
"available" time. The primary use case for this is for users to express
their "office hours" (e.g., Monday-Friday, 9am-5pm) in a standard way to
ensure free busy lookups show the correct periods of availability.

- Define a set of new iCalendar properties and parameters to standardise
some existing experimental X- properties in common use, based on a
survey of existing implementations.

- Define a set of new iCalendar properties and parameters to cover key
uses cases that implementers have identified, including, but not
limited to, a new "IMAGE" property (to allow embedding/linking of
images tied to a specific event), and a "CONFERENCE" property (to allow
embedding information about dial-in numbers and similar multi-party
communication options for an event).

The working group will work under the following parameters:

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

- For each set of extensions, examine their impact on the iTIP protocol
(RFC 5546), and define any necessary extensions to iTIP to accommodate
such impact.

- For each set of extensions, examine their impact on the CalDAV
protocol (RFC 4791), and define any necessary extensions to CalDAV to
accommodate such impact. Interface with the httpbis working group to
ensure that any CalDAV changes are consistent with good http practices.

The working group will use the following drafts as initial input for its

The following are out of scope for the working group:

- Any change that impacts backwards compatibility with existing
deployed iCalendar/iTIP/CalDAV clients and servers will be discussed
by the working group with a view to minimizing disruption to deployed
implementations without compromising desirable new function.

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


Date Milestone
Aug 2019 Submit scheduling controls document to IESG for publication
Jun 2019 Send JSCalendar draft to IESG
Jun 2019 Send iCal relation draft to IESG
Jun 2019 Send Event Publication draft to IESG
Apr 2019 Adopt a document for subscription upgrade
Apr 2019 Adopt a document for consensus scheduling
Apr 2019 Update charter/milestones to reflect current and planned work
Apr 2019 Send attachment dratf to IESG
Done Submit extensions draft to IESG for publication
Done Submit availability draft to IESG for publication
Done WG adoption of an extensions draft
Done WG adoption of an availability draft
Done Submit non-Gregorian recurrence rule draft to IESG for publication