RE: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

Yes, we would need XSD 1.1 to do this – there was a new attribute added to <any> to exclude namespaces.

 

But the real problem is not the use of ##other exactly, but the use of “lax” in combination with arguably non-conformant commercial validation tools that treat “lax” as a top level, “must ignore the schema  even though it is provided”.  That’s not the XSD definition of “lax” which is supposed to be a best effort.

 

My personal view is that we should go to strict and thus require the foreign namespace schemas during validation.

 

Regards,

 

                Mike

 

From: Andreas Tai [mailto:tai@irt.de] 
Sent: Monday, July 22, 2013 7:12 AM
To: Glenn Adams
Cc: Michael Dolan; public-tt
Subject: Re: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

 

>  I'm not sure it is possible to say ##other minus {ttm,ttp,tts} namespaces, or at least I haven't tried doing this with XSD. 

This is not possible with XML Schema 1.0. If the extensibility of TTML elements with "foreign namespace" attributes is implemented with the XML Schema  anyAttribute element, this will automatically open the door for potential false positive messages. Therefore documents that use undefined attributes  in (some) TTML namespaces will validate although this is not allowed.

Best regards,

Andreas 

Am 17.07.2013 04:04, schrieb Glenn Adams:

 

On Tue, Jul 16, 2013 at 6:42 PM, Michael Dolan <mdolan@newtbt.com> wrote:

Agreed.  The new XML schema currently permits style attributes, and should be corrected.

 

This is a side effect of having added ##other to core attributes in resolving ISSUE-150 [1][2].

 

[1] http://www.w3.org/AudioVideo/TT/tracker/issues/150

[2] http://dev.w3.org/cvsweb/2008/tt/spec/xsd/Attic/ttaf1-dfxp-core-attribs.xsd.diff?r1=1.3;r2=1.4;hideattic=0;f=h

 

I'm not sure it is possible to say ##other minus {ttm,ttp,tts} namespaces, or at least I haven't tried doing this with XSD.

 

Unrelated, but also about the schema, I thought we had found the authoritative xml.xsd on ww3.org a while back and we were going to defer to that and not include our own copy?

There is a problem with the xml.xsd you refer to [3]: namely, it types xml:lang as xs:language, but xs:language [4] doesn't admit the empty string, which is a legal value according to XML 1.0 [5].

 

[3] http://www.w3.org/2001/03/xml.xsd

[4] http://www.w3.org/TR/xmlschema-2/#language

[5] http://www.w3.org/TR/REC-xml/#sec-lang-tag

 

                Mike

 

From: Glenn Adams [mailto:glenn@skynav.com] 
Sent: Tuesday, July 16, 2013 4:49 PM
To: public-tt
Subject: Re: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

 

I was reviewing the recently closed ISSUE-257 today, and after further consideration, have determined it was incorrect, and needed to be reverted which I have done in [1].

 

The basic problem with the previous resolution is that TT Style Attributes are not defined for use on the tt element (with the exception of the special case of tts:extent). Furthermore, the outermost Content element [2] used during content style inheritance is the body element.

 

Ultimately, there is no element on which tts:fontSize can be specified that doesn't have a parent element. In the case of body, if no tts:fontSize is specified, then region style inheritance comes into effect. So that leaves us with a tts:fontSize potentially specified on region as the outermost inheritable font size. Accordingly, if the region's font size is specified in percentage, then we do need to resolve it against something other than its parent, since no ancestor of region participates in style inheritance.

 

I will now re-implement a fix for this issue based on the need to resolve percentage on region. 

 

[1] https://dvcs.w3.org/hg/ttml/rev/0355e9473d7e

[2] https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttaf1-dfxp.html#element-vocab-type-content

 






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