Fix links to TTML2 versions referenced by IMSC documents

[thomasheritage]

IMSC 1.2: https://www.w3.org/TR/ttml-imsc1.2/#bib-ttml2 says:

Timed Text Markup Language 2 (TTML2) (2nd Edition). Glenn Adams; Cyril Concolato. W3C. 28 January 2020. W3C Candidate Recommendation. URL: https://www.w3.org/TR/ttml2/

IMSC 1.3: https://w3c.github.io/imsc/imsc1/spec/ttml-ww-profiles.html#bib-ttml2 says:

Timed Text Markup Language 2 (TTML2) (2nd Edition). Glenn Adams; Cyril Concolato. W3C. 9 March 2021. W3C Candidate Recommendation. URL: https://www.w3.org/TR/ttml2/

But all four links quoted above actually take you to TTML2 W3C Recommendation 08 November 2018 (which I believe is the first edition)

Related info

Unhelpfully the TTML "cover page" at https://www.w3.org/TR/ttml/all/ lists:

Candidate Recommendation Snapshot
Timed Text Markup Language 2 (TTML2) (2nd Edition)
9 March 2021

but again, this is actually a link to to TTML2 W3C Recommendation 08 November 2018 (first edition)

If you do manage to find the correct link:
https://www.w3.org/TR/2021/CR-ttml2-20210309/
the top of the document lists:

Latest version:
https://www.w3.org/TR/ttml2/

which seems unhelpful because it takes you back to the first edition...
I suppose that should say "latest approved version" (?) rather than "latest version" (the IMSC documents have "Latest published version" and "Latest editor's draft")

Note that https://www.w3.org/TR/dapt/#bib-ttml2 does not have the same problems, linking correctly to the 2nd Edition:

Timed Text Markup Language 2 (TTML2) (2nd Edition). W3C. 2021-03-09. URL: https://www.w3.org/TR/2021/CR-ttml2-20210309

[nigelmegitt]

Thank you for flagging this @thomasheritage !

[palemieux]

@nigelmegitt Should IMSC 1.3 use the same dated reference to TTML2 that DAPT uses? We would lose the reference to the supposedly latest and undated TTML2 (https://www.w3.org/TR/ttml2/), but, as @thomasheritage , this turns out to be not the latest in any case.

[nigelmegitt]

I would say so yes, @palemieux .