Define ttm:role values solely via the role registry

[nigelmegitt]

Defined values of ttm:role are both listed in the specification and referenced as a separate registry at https://www.w3.org/wiki/TTML/RoleRegistry but it is not clear what the process is for adding new values (such as those needed for DAPT )

Suggest removing the hard coded list from TTML2 and using the W3C's Registry Track for making the Registry the normative list.

[nigelmegitt]

See also w3c/dapt#24 (comment)

[css-meeting-bot]

The Timed Text Working Group just discussed ttm:role values in the registry, and agreed to the following:

• RESOLUTION: Define a registry track document with the list of TTML role values and normatively reference it from TTML2

The full IRC log of that discussion

<nigel> Subtopic: ttm:role values in the registry
<nigel> github: https://github.com//issues/1248
<cyril> scribe: cyril
<nigel> scribe+ cyril
<cyril> nigel: since we published this version of TTML2, there is now a Registry track in the Process with its own publication cycle
<cyril> ... it's recognized that it's just data values
<cyril> ... I'd like to modify this in TTML2 to reference the registry
<cyril> ... at the very least we need to assign a document (possibly the wiki) as the registry and reference it from the spec
<cyril> cyril: we already do
<cyril> nigel: it's informative
<cyril> nigel: I'll look into reversing that
<cyril> ... and btw it's exactly the same in TTML1
<cyril> ... any thoughts or comments?
<cyril> atai: currently the role registry is not normative
<cyril> ... there is no rule to add values, constraints on duplicate values ...
<cyril> ... if a new role is defined in a TTWG spec it would not go into TTML2 but only in the registry and be normative
<cyril> nigel: correct
<nigel> q?
<cyril> ... it allows us to change that list without having to redo the entire spec
<cyril> nigel: no objections?
<cyril> (silence)
<cyril> nigel: we need to determine the place (wiki or not) and rules for registry changes
<cyril> ... I take that as an action
<atsushi> q+ for not sure but registry is normatively referencable???
<cyril> ... Proposal: Define a registry track document with the list of TTML role values and normatively reference it from TTML2
<cyril> atsushi: I'm not sure about the registry
<cyril> RESOLUTION: Define a registry track document with the list of TTML role values and normatively reference it from TTML2

[nigelmegitt]

I will provide a first draft proposal to meet the requirements of https://www.w3.org/2021/Process-20211102/#registries for a registry.

[nigelmegitt]

Although we agreed to do this, w3c/dapt#54 would remove the dependency on this issue for DAPT.