[imsc] Non-prohibition of partially supported features. (#488)

skynavga has just created a new issue for https://github.com/w3c/imsc:

== Non-prohibition of partially supported features. ==
In §6 it is stated

>All features specified in [ttml2] are prohibited unless specified otherwise below

however, there appears to be no prohibition against the use of features that are marked as _partially supported_.

For example, `#base-version-2` includes support for `#base-general`, and §6 marks `#base-version-2` as "partially supported via #base", but does not otherwise state that the underlying features of `#base-version-2` that are not included in the underlying features of `#base` are prohibited.

The same comment applies to all other partially supported features.

If the intention is to prohibit underlying features not covered by statements of only partial support, then I would expect a general normative statement to be present that states something like:

>If a feature or extension is marked as partially supported, then the vocabulary, syntax, and attribute values of the feature or extension that are not included in the statement of partial support are prohibited.

This text should probably go into §4 _Conformance_.

Please view or discuss this issue at https://github.com/w3c/imsc/issues/488 using your GitHub account

Received on Tuesday, 24 September 2019 03:55:12 UTC