Remove explicit animation, styling and timing from break (br) element.

[skynavga]

There appears to be insufficient demand to support explicit animation, styling or timing on the <br/> element. It is expected that TTML1 3e will recommend against use of animation children, so there is an opportunity to deprecate or obsolete animation children in TTML2, in which case it makes sense to remove (the only recently added - in TTML2) styling and timing as well.

See also ttml1/#325.

[nigelmegitt]

Note in addition that if for some reason styling, animation or timing are needed on a <br> element then it can be wrapped in a <span> on which they are specified.

[css-meeting-bot]

The Working Group just discussed Remove explicit animation, styling and timing from break (br) element. ttml2#552, and agreed to the following resolutions:

• RESOLUTION: Align the content model of br in TTML2 with TTML1 and make the recommendation about animation on br stronger by deprecating it in TTML2.

The full IRC log of that discussion

<nigel> Topic: Remove explicit animation, styling and timing from break (br) element. ttml2#552
<nigel> github: https://github.com/w3c/ttml2/issues/552
<nigel> Nigel: If we do this, then will it cause any incompatibilities with TTML1 documents that
<nigel> .. use the syntax?
<nigel> Pierre: Will the prohibited content be pruned prior to validation?
<nigel> Glenn: I'd say this is borderline.
<nigel> Pierre: We have already disrecommended the syntax in TTML1 Third Edition.
<nigel> .. We can disrecommend it from TTML2 and prohibit it from a later version of TTML.
<nigel> Glenn: Ok.
<nigel> Cyril: I'm not sure how to implement this. Is it correct to match TTML1 and remove things
<nigel> .. introduced in TTML2?
<nigel> Pierre: Change the disrecommendation to a deprecation.
<nigel> Nigel: +1
<nigel> Glenn: +1
<nigel> Cyril: TTML1 did not talk about styling, just animation and timing.
<nigel> Pierre: Styling and timing were added in TTML2 and need to be removed to match TTML1.
<nigel> Cyril: No TTML1 has styling.
<nigel> Pierre: It doesn't have timing.
<nigel> Cyril: What should we do with style?
<nigel> Glenn: We don't need to do anything because no style attribute in TTML1 applies to br.
<nigel> .. Whether the attributes are present or not is academic.
<nigel> Pierre: I agree with Glenn - the only thing is to remove timing and deprecate animation.
<nigel> Cyril: That's fine by me, I can do that.
<nigel> Glenn: We need to check if any style is now applicable to br.
<nigel> Cyril: Okay I'll check and add it to this issue if there are any.
<nigel> RESOLUTION: Align the content model of br in TTML2 with TTML1 and make the recommendation about animation on br stronger by deprecating it in TTML2.
<nigel> Glenn: Specifically we are removing animate, begin, dur, end, region and timeContainer.