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ISSUE-178: initial values and style set calculations are unclear, especially for transformable attributes [DFXP 1.0]

From: Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Thu, 23 Aug 2012 14:58:22 +0000
Message-Id: <E1T4YrW-00032o-2h@tibor.w3.org>
To: public-tt@w3.org
ISSUE-178: initial values and style set calculations are unclear, especially for transformable attributes [DFXP 1.0]

http://www.w3.org/AudioVideo/TT/tracker/issues/178

Raised by: Mike Dolan
On product: DFXP 1.0

The style set calculation of section 8.4 is unclear in relation to initial values, and especially for attributes that are defined to be transforms of the parent value.

For example, in a document that otherwise does not define tts:fontSize, the occurrence of tts:fontSize=”200%” (as I understand the text, and at least for the % metric) is a transformation of the attribute's initial value (1c) resulting in effective fontSize of 2c.

And, it is unclear that it is at all possible to set a different initial value (e.g. on <tt>).

Also, these transformable attribute definitions do not clearly distinguish that the behavior is apparently metric-dependent. For example, the fontSize text says: "...font size is interpreted as a scaling transform to the font's design EM square". Although % works as I describe above, px, c and em really cannot (or if they do, how?).

In addition to clarifying the definitions of these attributes, to help illustrate the effect of initial values it would be useful to explicitly set various attributes in some example document and define the resulting attribute value, perhaps in the example intermediate synchronic documents of 9.3.4, which might include an explicit setting of all initial values.
Received on Thursday, 23 August 2012 14:58:23 GMT

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