[ttml2] Define `ttm:role` values solely via the role registry (#1248)

nigelmegitt has just created a new issue for https://github.com/w3c/ttml2:

== Define `ttm:role` values solely via the role registry ==
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](https://w3c.github.io/dapt/) )

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

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/1248 using your GitHub account


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Received on Wednesday, 14 September 2022 17:21:59 UTC