Does "implicit" begin value mean the "default" value of the begin attribute?

[palemieux]

The following is incorrect: in the case of a child of a sequential container, the implicit begin time is equal to the desired end time of the previous sibling, or the desired begin time of the parent if no previous sibling exists.

As defined by [SMIL 3.0], § 5.4.3, if no begin attribute is explicitly specified on a timed element, then a default (implicit) value is determined by the nearest time container ancestor; however, in TTML, that ancestor is either a parallel time container or a sequential time container, both of which apply a default value of 0.

Suggest referring to SMIL, and not elaborating.

[nigelmegitt]

This TTML text is interpretation-dependent. In a seq time container the implicit value that makes the begin time equal to the end time of the previous sibling is 0. So arguably the text is not wrong. It could be clarified perhaps.

[palemieux]

It could be clarified perhaps.

Yes... or as in the case of TTML1, the note could simply state:

if no begin attribute is explicitly specified on a timed element, then a default (implicit) value is determined according to SMIL3

[skynavga]

First, there is no error here. Second, you are equating "implicit" and "default" (attribute value), which is not correct.

[nigelmegitt]

@palemieux I cannot find that text in TTML1 Second Edition - pointer please?

[palemieux]

@nigelmegitt See https://w3c.github.io/ttml1/index.html#timing-attribute-begin

[palemieux]

@skynavga I am surprised by your lack of enthusiasm given your general objective of reducing duplication and explanatory notes. Furthermore, I am not the one equating "implicit" and "default" (attribute value), the current text does by stating: _default (implicit) value _

[nigelmegitt]

@palemieux Sorry, I still can't see it. The TTML1 note looks like this to me:

See [SMIL 2.1], § 10.4.1, Begin value semantics when no begin attribute is specified.

That doesn't look like what you put in #590 (comment)

[palemieux]

@nigelmegitt I was making a concrete proposal based on the current TTML2 text. For the record, I prefer the note as it stands in (draft) TTML1 3ED.

[nigelmegitt]

@palemieux Right, I see. Reviewing the change in TTML2, I agree with this issue, that the note text is certainly wrong right now, for the reasons described in the issue (first comment).