Clarify use of 'applies to' in style property definition tables (#1088).

[skynavga]

Closes #1088.

[palemieux]

If the CSS definition is going to be used, then it should be used verbatim, without the extraneous moreover....

[cconcolato]

The CSS specification seems clear that the "applies to" line is normative and not "intended to be of a general nature" without normative impact as the PR seems to suggest.

1.4.2.3 Applies to
This part lists the elements to which the property applies. All elements are considered to have all properties, but some properties have no rendering effect on some types of elements. For example, the 'clear' property only affects block-level elements."

What matters is for implementers to be sure that if the condition given in the "applies to" line is not meant, then they can ignore the property for rendering (not for inheritance).

[nigelmegitt]

I could accept just the CSS definition. In other words, in the proposal, delete "Moreover" and all the new text after it.

[palemieux]

The updated prose resolves my comment at #1089 (review) . I am keeping my blocker so that all related PRs can be evaluated in light of #1043

[skynavga]

I'd like to point out that XSL-FO 1.1 includes the following elaboration in its use of applies to in Appendix B.4 (emphasis added).

For each property the formatting objects it applies to is listed. It should be noted, however, that for some formatting objects there are qualifications on applicability or values permitted.

Since TTML based its original use of applies to on XSL-FO, by way of analogy, we should probably include this elaboration in the note proposed by this PR.

[nigelmegitt]

@skynavga I don't think the elaboration adds much of any use: if the Applies to row on the style attribute table further qualifies the set of elements, that is obvious from the context. I don't think there's anything incorrect in the content of the elaboration though.

[skynavga]

@nigelmegitt the point of my mentioning this was that XSL-FO is saying that the prose of style property definitions define further qualifications on applies to, and that the appendix B.4 (in XSL-FO), which effectively serves the same function of our (and CSS's) applies to entry in style property definition tables, does not itself specify such qualifications: meaning, we do not need to place such qualifications in our applies to table entries either, and might want to add similar language in this PR beyond simply citing CSS;

[nigelmegitt]

@skynavga that may well be the intent of the text but taking it out of context and just looking at the additional sentence, there's nothing to indicate where the additional qualifications are specified, so it doesn't serve the purpose you may have been hoping it does.

Even with the additional context behind the proposal I still think that transplanting it into TTML would not add anything useful, and for that reason I think we should not do so.

[css-meeting-bot]

The Timed Text Working Group just discussed Clarify use of 'applies to' in style property definition tables (ttml2#1088)..

The full IRC log of that discussion

<nigel> Topic: Clarify use of 'applies to' in style property definition tables (ttml2#1088).
<nigel> github: https://github.com//pull/1089
<cyril> scribe: cyril
<cyril> nigel: this one is about 'applies to'
<cyril> ... we're looking at pull 1089
<cyril> ... this PR adds a note
<cyril> pal: that should be part of the broader discussion
<cyril> ... in isolation it makes sense
<cyril> ... the real issue is what do we write in "applies to"
<cyril> glenn: are you asking us to approve or not the whole collections of PR? as a whole?
<cyril> ... the intent was dividing them because they are orthogonal
<cyril> nigel: if we can't agree on what 'applies to' mean, we cannot move on
<cyril> pal: depending on the context of applies to the meaning might change
<cyril> nigel: if we know what 'applies to' should mean, then we can put it
<cyril> ... the current proposal says make it say what CSS does
<cyril> nigel: are you agreeing?
<cyril> pal: I think we should assume that that's the case and move forward
<cyril> ... let's not merge now
<cyril> glenn: I think the chair needs to make a determination on how to move forward
<cyril> nigel: we have agreement can we move forward?
<cyril> glenn: Pierre has put a blocker for process reasons and I don't agree with
<cyril> nigel: moving forward means having a common ground
<cyril> ... is there any objection to adding this text?
<cyril> ... hearing nothing, we have agreement in principle
<cyril> glenn: before you move on, we have 2 approvals on this PR but a blocker
<cyril> ... we need Pierre to remove his blocker
<cyril> nigel: I'm sure Pierre will remove his blocker
<cyril> github: https://github.com//pull/1079
<cyril> github: https://github.com//pull/1089

[skynavga]

I am withdrawing this PR and closing it since no progress appears possible.

[skynavga]

Based upon today's TTWG call, we have full approval to merge this (which I reopened above).