Add IMSC profile designators to Table 5-2.

[skynavga]

At present, IMSC's use of profile designators in the TT Profile Namespace is technically out of compliance with TTML2 due to the following language:

TTML2 (1e) §5.2.3

All profile designators which have the TT Profile Namespace as a prefix but are otherwise not listed in Table 5-2 – Profiles are reserved for future standardization, and must not appear in a conformant document instance.

To fix this, we need to add entries to Table 5-2 for IMSC's text and image profiles (both 1.0 and 1.1).

[skynavga]

@palemieux language equivalent to the above also appears in TTML1 (3e) in §5.2; you might want to open an issue in https://github.com/w3c/ttml1/issues

[nigelmegitt]

Hmm, that text does not say who can do the "future standardisation" or in what documents it may be done. Arguably it should be okay for TTWG to define other profiles in other documents. Imposing a constraint that the only place where those profiles may be defined is in TTML itself is overly restrictive in my opinion, since it prevents even TTWG from defining any other profile unless TTML1 and TTML2 are also amended to suit.

I would prefer to describe in further detail where such profiles may be defined (and found), and further, I propose that the location for that is the TTML Profiles document, which seems like the best place for it, and can be updated without modifying the core TTML specification.

[palemieux]

+1 to https://github.com/w3c/ttml2/issues/1034#issuecomment-452664578 , with the added clarification that the use of the TT Profile Namespace is reserved for W3C, unless already stated elsewhere or obvious.

[css-meeting-bot]

The Timed Text Working Group just discussed Add IMSC profile designators to Table 5-2. ttml2#1034.

The full IRC log of that discussion

<nigel> Topic: Add IMSC profile designators to Table 5-2. ttml2#1034
<nigel> github: https://github.com/w3c/ttml2/issues/1034
<cyril> glenn: I reviewd that and the suggested approach looks reasonable to me and I will prepare a PR
<cyril> nigel: thank you, done, then

[skynavga]

[deleted]

[nigelmegitt]

@skynavga https://github.com/w3c/ttml2/issues/1034#issuecomment-505320194 is confusing: it's a duplicate of the issue, which has already been discussed and an approach agreed. Please could you re-review the discussion on this issue?

[skynavga]

Thanks for pointing that out. I will delete the (redundant) comment.

[skynavga]

Ah, right. I will change the PR to normatively reference the profiles registry document instead of further enumerating profiles in TTML itself.

[nigelmegitt]

Thank you @skynavga - does it need to be normative?

I think it can be informative: the TTML profiles registry is merely one listed location where W3C might publish TTML profiles.

I agree the normative statement does need to be changed: it needs to say that W3C can publish profiles of TTML, rather than requiring them to be within the TTML specification itself.

[skynavga]

It must be a normative reference since it is referred to in normative text and has real conformance impact (which is why this issue and PR are marked as substantive).

[skynavga]

@nigelmegitt also, there is (and will be) only one TTML profile registry, regardless of where the profiles themselves are published

[nigelmegitt]

@skynavga regarding https://github.com/w3c/ttml2/issues/1034#issuecomment-505320194 in the future please do not delete comments; for consistency and the archive if you need to advise the group that a comment was in error, add a new message asking for the previous one to be disregarded. @plehegar tells me that this is what he would generally expect in line with the W3C's archive policies.

[nigelmegitt]

@skynavga ok, I'm persuaded it needs to be normative.

[skynavga]

@nigelmegitt I did not delete the comment, I edited it, replacing it with "[deleted]"; if someone wants to look at the prior content of the comment, they only have to click on the "edited" link to see past history;