Missing text how attributes in IMSC Style namespace should be processed

[andreastai]

It is not clear that all attributes in the IMSC style namespace should be handled the same way as TTML style attributes. It is somehow implicit, but there is no direct evidence. For TTML, all extensions in foreign namespaces are completely opaque. "IMSC Style namespace" vocabulary is the same as a "Foo namespace". The referencing standard needs to define how the new features are "positioned" in the TTML specification model.

This could be done by saying that the introduction text in Section 8 of TTML 1 and Section 8.4 also apply to all attributes defined in the IMSC Style namespace.

[nigelmegitt]

@TairT Please could you clarify what you mean by " "positioned" in the TTML specification model"? Are you talking about syntactic constraints, for example?

[andreastai]

@nigelmegitt Can you point me to text in IMSC that Section 8.4 of TTML1 apply to itts:attribute::* ?

[nigelmegitt]

@TairT Ah, I think I see what you mean: are you asking for the semantics of style association, inheritance, resolution value mapping and processing to be clarified for the extensions that apply to content elements, i.e. to state explicitly that the same rules apply to extension styling attributes (which should be listed) as to TTML styling attributes?

Sorry I didn't get this was what you meant at first.

[andreastai]

@TairT Ah, I think I see what you mean: are you asking for the semantics of style association, inheritance, resolution value mapping and processing to be clarified for the extensions that apply to content elements, i.e. to state explicitly that the same rules apply to extension styling attributes (which should be listed) as to TTML styling attributes?

Yes

[palemieux]

It looks like TTML1 uses the term "style property" to tie styling attributes with the Style Resolution Processing procedure.

I propose adding the following text:

The following style properties are subject to the Style Resolution procedures specified at Section 8.4 of TTML1:

• itts:fillLineGap
• itts:forcedDisplay
• ebutts:linePadding
• ebutts:multiRowAlign

I think it is ok to add to IMSC 1.0.1 as long as no one construes this as substantive change, otherwise I suggest scheduling it for IMSC 1.1

[andreastai]

@palemieux I agree!