Change reference to TTML2 to a dated reference

[nigelmegitt]

No description provided.

[css-meeting-bot]

The Working Group just discussed IMSC reference to TTML1, and agreed to the following:

• SUMMARY: Discussion ongoing, group leaning towards a specific dated reference to TTML

The full IRC log of that discussion

<nigel> Topic: IMSC reference to TTML1
<nigel> Nigel: Do we have an issue about the reference?
<nigel> Pierre: IMSC 1.0.1 references the latest TTML1
<nigel> Nigel: It's not raised as an issue.
<nigel> Glenn: We haven't discussed this - it is an open question.
<nigel> Pierre: Presumably the difference between editions is to correct bugs and things that ought to be fixed.
<nigel> .. So it doesn't seem unreasonable for a profile of TTML1 to reference the latest edition.
<nigel> .. I could be persuaded otherwise.
<nigel> Glenn: Up until 3rd Ed we insisted on only editorial changes, but in 3rd ed there are substantive changes.
<nigel> Pierre: Yes, but regardless of whether the changes were substantive, they are bug fixes,
<nigel> .. not feature additions. So if someone comes in and says "which version should I implement"
<nigel> .. we would always say the latest edition.
<nigel> s/version/edition
<nigel> Philippe: Yes, that's what our system would say as well.
<nigel> Glenn: It would be interesting to get other feedback on this, Mike may have a different view.
<nigel> Nigel: Yes, it's a technical issue - if an implementor implements the spec precisely following
<nigel> .. the latest edition and then that changes underneath, then the state of conformance of
<nigel> .. that implementation is unclear. It could be that it's not a big enough problem to worry about.
<nigel> Pierre: Yes I could be persuaded either way.
<nigel> .. This is confusing from an external point of view too and causes arguments. Maybe I'm
<nigel> .. persuading myself to point to a specific edition.
<nigel> Glenn: In the case of TTML1 referencing XML we point to a specific version/edition of XML
<nigel> .. so that doesn't arise.
<nigel> Nigel: It seems to be a matter of good practice to reference a specific version but in doing that
<nigel> .. to accept that if the referenced spec changes then the referring spec needs to be updated
<nigel> .. and that should be transparent.
<nigel> Glenn: In TTML we have references to XML 1.0 and XML 1.1 and both have editions in the title.
<nigel> Philippe: Which link do you use?
<nigel> Glenn: We use the dated links.
<nigel> s/references/normative references
<nigel> Glenn: The title has the edition and the link is dated. That's the practice we followed in TTML.
<nigel> Pierre: Listening to this I'm starting to lean towards referencing a specific version in IMSC 1.1.
<nigel> .. Maybe it wasn't a good idea in IMSC 1.0.1 to reference TTML1 without dates.
<nigel> Philippe: The only problem is if you reference a dated version and you make a security
<nigel> .. update that you want everyone to pick up then they won't.
<nigel> Pierre: The tooling on W3C... Imagine IMSC 1.1 makes a hard reference to TTML1 2nd Ed.
<nigel> .. Imagine in the meantime it was superseded because of a terrible security bug. When you
<nigel> .. get to it you would get a huge warning saying "don't use this"?
<nigel> Philippe: yes
<nigel> Pierre: Doesn't that address the issue.
<nigel> Philippe: If you don't mind this then realise that at the end you are directing the reader to
<nigel> .. a specific version.
<nigel> Pierre: At least it gives the reader the ability to do a diff and see what changed.
<nigel> .. It also means, to Nigel's point, that as a group we have to be more active in updating stuff.
<nigel> .. It is more work for us but it's more precise maybe.
<nigel> Philippe: If you guys believe there is the use case to be that precise then sure. At the end of
<nigel> .. the day it does not matter which reference you state, people are going to use whichever
<nigel> .. XML parser they are familiar with. They're not going to write their own.
<nigel> Glenn: On the other hand, from a point of view of conformance and testing you might have
<nigel> .. an issue there, but that's a separate point. Right now we have referential integrity
<nigel> .. with respect to TTML references. We went through TTML2 recently.
<nigel> .. When we refer to RFC we don't have this issue, because they don't change the text.
<nigel> Nigel: They change the text to point the reader to a newer version.
<nigel> Glenn: That's true, but it doesn't change conformance wrt that spec.
<nigel> Philippe: This is topical because the AB is discussing living standards.
<nigel> Pierre: In some groups people want to be precise because they are putting stuff on shelves
<nigel> .. for years and they want to know exactly which versions they reference.
<nigel> Glenn: I'm reminded of DOS, and switches in code to handle different compatibility bits.
<nigel> .. That's what you end up with when you were very precise.
<nigel> Nigel: There's a precise mirror here with python, node, java etc with tests for a piece of software
<nigel> .. passing given a specific set of 3rd party library versions, and capturing a freeze point
<nigel> .. of those versions. We could do that with our specs, and associate a test suite with a specific
<nigel> .. set of reference versions.
<nigel> Glenn: Right now the tests are based on a specific version of a spec, you could make that
<nigel> .. the other way around.
<nigel> .. In the case of XML 1.1 it refers to the specific edit in place date.
<nigel> Nigel: I'm not sure if we need an issue against IMSC 1.1 to reference a specific version of TTML2?
<nigel> Glenn: I heard Pierre say he is leaning towards doing that.
<nigel> github: https://github.com//issues/381
<nigel> SUMMARY: Discussion ongoing, group leaning towards a specific dated reference to TTML

[palemieux]

Recommend referencing TTML2 CR2 with a plan to update the reference to published TTML2 with the understanding that such a change will not be substantive since no substantive changes can be made to TTML2 CR2.