Improve non-negative-real interoperability (#943).

[skynavga]

Closes #943.

[nigelmegitt]

Marking for the agenda, since as per #943 (comment) the deadline for a change like this seems to have passed, even though it is (probably) a good idea. The alternative would be to defer to 2nd Ed.

[css-meeting-bot]

The Working Group just discussed Improve non-negative-real interoperability (#943). ttml2#944, and agreed to the following:

• SUMMARY: Close pull request and mark as TTML.next.

The full IRC log of that discussion

<nigel> Topic: Improve non-negative-real interoperability (#943). ttml2#944
<nigel> github: https://github.com//pull/944
<nigel> Glenn: I have no problem deferring this to 2nd Ed, and note that if we do that then we
<nigel> .. need to approve #956 in the meantime.
<nigel> Nigel: This is about making the value "0." that is illegal in TTML1 legal by adopting xs:decimal.
<nigel> .. I think we should do nothing and nobody will care.
<nigel> Glenn: If we don't do it then we have to do #956.
<nigel> Nigel: Any other views on this?
<nigel> [group]: silence
<nigel> Glenn: The reason #956 is important is that if we use xs:decimal in our schema then all
<nigel> .. the tools that take the schema will make it impossible to tell if 0. was used because the
<nigel> .. resulting value will be a double floating point number whose original lexical value will
<nigel> .. be lost. Changing it to a string will pass that through to implementations.
<nigel> Nigel: And the XSD is not normative and it is not a requirement for implementers to use it.
<nigel> Glenn: Sure.
<nigel> Nigel: There are no comments on this.
<nigel> Glenn: I will move this issue to TTML.next.
<nigel> Nigel: OK
<nigel> SUMMARY: Close pull request and mark as TTML.next.

[skynavga]

Deferring to consideration under ttml.next.

[palemieux]

The pull request is missing tests to exercise the change.

[nigelmegitt]

Tests at w3c/ttml2-tests#208 look good.