[calsify] URI properties in iCalendar

[Ben Fortuna <[e-mail]>]

Hi calext WG,

I have a query about the use of URI as a property type in iCalendar. I have reviewed the last couple of IETF calls and I think this may be a good place to ask.

STATUS/CLASS

I feel there is a limitation in the current iCalendar spec for some properties with a finite set of values.

For example, CLASS supports {PUBLIC|PRIVATE|CONFIDENTIAL}, and may be extended formally (iana-token) or informally with x-name values. [1] Whilst x-name is the intended way to support vendor-specific values, it doesn't really lend itself to formally defined extended values (i.e. via a referable schema), in the way a URI value could.

Similarly, STATUS supports a finite value set specific to each component type, but has no allowance for extension either formally or informally. [2] This can be an impediment to how, for example, tasks can be mapped from different systems such as JIRA, which allow a much more expanded and customizable set of values. [3]

I did note that the iCalendar task extensions draft introduces a new SUBSTATE property for improved granularity, but is still restricted to only formal extension via iana-token. [4]

URI Values

I think a possible solution to extension may be via support for URI values, in the same way as the recently introduced CONCEPT property. [5] This would allow for a finite set of extended values to be formally defined, without being limited by the iCalendar specifications.

One challenge I guess is how to handle extended values not supported by a CUA implementation. I see this as less of an issue for STATUS/CLASS as they are both optional properties (in all components?), so could safely be ignored if a value is not recognized.

So I guess I am wondering if you see URI as a possible or desirable approach to extended values in the future?

[1]: https://www.rfc-editor.org/rfc/rfc5545.html#section-3.8.1.3

[2]: https://www.rfc-editor.org/rfc/rfc5545.html#section-3.8.1.11

[3]: https://support.atlassian.com/jira-cloud-administration/docs/what-are-issue-statuses-priorities-and-resolutions/

[4]: https://www.ietf.org/archive/id/draft-ietf-calext-ical-tasks-07.html#name-sub-state

[5]: https://www.rfc-editor.org/rfc/rfc9253.html#name-concept

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Ben Fortuna

https://www.linkedin.com/in/benfortuna|https://github.com/benfortuna