Re: ISSUE-367 (#textAlign clarification): Clarify initial value override for tts:textAlign [TTML IMSC 1.0]

On Tue, Jan 27, 2015 at 10:01 AM, Timed Text Working Group Issue Tracker <
sysbot+tracker@w3.org> wrote:

> ISSUE-367 (#textAlign clarification): Clarify initial value override for
> tts:textAlign [TTML IMSC 1.0]
>
> http://www.w3.org/AudioVideo/TT/tracker/issues/367
>
> Raised by: Nigel Megitt
> On product: TTML IMSC 1.0
>
> The feature list in §7.4 of the IMSC 1 CR specifies for #textAlign:
>
> > MAY be used. The initial value of tts:textAlign shall be "center" for
> the default region. NOTE: This is consistent with [ST2052-1].
>

this is not compatible with TTML1, so it needs to be removed unless you are
willing to sacrifice TTML1 interoperability;

in TTML2, the author can include the following in the <styling> element:

<styling>
<initial tts:textAlgin="center"/>
...
</styling>


>
> This is somewhat subtle, and doesn't indicate that it's a variation from
> TTML1SE. I propose the following edited version:
>
> > MAY be used. The initial value of tts:textAlign shall be "center" for
> the default region only. NOTE: This is consistent with [ST2052-1] but
> differs from TTML1SE. Document authors are recommended not to rely on the
> initial value for text alignment in the default region but to specify the
> tts:textAlign attribute explicitly to generate the expected presentation by
> both generic TTML1SE and IMSC 1 presentation processors.
>
> I also propose appending this wording to the #layout feature in §6.10:
>
> > NOTE: Authors are recommended to define and reference a region rather
> than relying on the default region, to avoid inconsistent presentation
> between generic TTML1SE and IMSC 1 presentation processors resulting from
> the different initial value of tts:textAlign for the default region. See
> also #textAlign.
>
> This is an editorial clarification rather than a substantive change.
>
>
>
>