Foreign namespace elements not reflected in syntax.

[andreastai]

Section 5.3.2

In addition to standardized extension vocabulary, a conforming document instance may contain arbitrary namespace qualified elements that reside in any namespace other than those namespaces defined for use with this specification.

This option seems not reflected in the content model description of TTML elements.

[skynavga]

We have discussed this before [reference needed], and concluded that foreign elements are indeed supported and need not be explicitly marked in content models. The reason for this is that those content models apply only to Abstract Document Types after pruning vocabulary from foreign namespaces (see https://w3c.github.io/ttml2/spec/ttml2.html#doctypes).

[skynavga]

See also #358, specifically, w3c/ttml1#196.

[andreastai]

Thanks for the pointer to the other issue. You are right that this has been discussed before. I will go back and check our discussion before I respond.

[skynavga]

@TairT please comment further if action is necessary; otherwise, please close

[andreastai]

I checked the links but I could not find a hint, that the allowance of foreign namespace elements need not to be reflected in the element content models. I can not see the difference why this is different from the allowance of foreign namespace attributes.

[skynavga]

Remove {any attribute not in default or any TT Namespace} should be removed on each element information item.

[skynavga]

Also update 14.1.1 element information item and add notes explaining that an implementation may or may not prune foreign vocabulary (but must do so for the purpose of validation processing).

[css-meeting-bot]

The Working Group just discussed Foreign namespace elements not reflected in syntax. ttml2#439, and agreed to the following resolutions:

• RESOLUTION: Remove text permitting foreign namespace attributes and elements in the content model, and add section explaining that they are permitted but are pruned for validation purposes.

The full IRC log of that discussion

<nigel> Topic: Foreign namespace elements not reflected in syntax. ttml2#439
<nigel> github: https://github.com//issues/439
<nigel> Andreas: In TTML1 for attributes it is explicitly marked in the syntax definition whereas for elements it is not.
<nigel> .. That seems inconsistent.
<nigel> Glenn: I agree there is an inconsistency and it is that we specify that foreign attributes
<nigel> .. are permitted when we should not say anything.
<nigel> .. For example the <p> element says {any attribute not in default or any TT Namespace}
<nigel> .. but that is not relevant because it will already have been pruned out. Since the validity
<nigel> .. checking only happens after pruning, what we really should do is take out that text.
<nigel> .. Somewhere in the document, e.g. in 4.1, we should state that depending on when you
<nigel> .. invoke the schema, you might get different results, and we assume post-pruning.
<nigel> Andreas: I would support taking out that text in the element attribute definitions.
<nigel> Nigel: Can we make an exception for metadata elements? Or are both elements and attributes
<nigel> .. pruned out of metadata elements?
<nigel> Glenn: Yes they are pruned there too.
<nigel> Nigel: I'm concerned that this change could give the misleading impression that foreign
<nigel> .. namespace attributes and elements are no longer permitted in TTML2. So we need to
<nigel> .. add some text to make it clear that we are not making that change.
<nigel> Glenn: Yes
<nigel> .. There are two example foreign namespace fragments under metadata. We should add notes
<nigel> .. that for the purpose of validation according to the content conformance model those
<nigel> .. foreign namespace attributes and elements would no longer be present in the abstract
<nigel> .. document instance but in some implementations they may choose to use that foreign namespace
<nigel> .. vocabulary for example in a DOM.
<nigel> Andreas: That makes sense. Then in §14.1.1 metadata we are removing the "any" for both
<nigel> .. foreign namespace attributes and elements would be removed?
<nigel> Glenn: That's correct.
<nigel> Glenn: I will propose a pull request.
<nigel> RESOLUTION: Remove text permitting foreign namespace attributes and elements in the content model, and add section explaining that they are permitted but are pruned for validation purposes.