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eg and ifo properties

From: Victor Mote <vic@outfitr.com>
Date: Fri, 24 Aug 2007 08:12:23 -0600
To: "XSL Editors" <xsl-editors@w3.org>
Cc: "'Max Berger'" <max@berger.name>
Message-ID: <002001c7e658$ca9213f0$6297880a@jackson>

Dear Editors:

During recent work to integrate our FO processor with a MathML processor,
several questions came up about what information can be passed from the FO
processor to the MathML processor. MathML content can be either in an
fo:external-graphic or an fo:instream-foreign-object, and these questions
apply to each of these FOs.

MathML allows at least some of its formatting properties to be inherited
from its surrounding text.[1] The question is: What are FO documents allowed
to provide to them? The properties in question for MathML are "color",
"font-size", and "background-color", but it is conceivable that
font-selection properties might be useful as well. None of these properties
"apply" to either fo:external-graphic or fo:instream-foreign-object in the
1.1 Recommendation.
[1] http://www.w3.org/TR/MathML/chapter3.html#presm.commatt

I see three possible answers to the question:
1. FO content and content from other namespaces have an arms-length
relationship, and the FO document should not directly affect the rendering
of the non-FO content, except as allowed for in fo:instream-foreign-object,
where FO and non-FO attributes may be passed to the processor of the non-FO
content.
2. The fact that certain properties "apply" to fo:external-graphic and
fo:instream-foreign-object does not prevent these objects from passing the
values of other properties to the processors of their content.
3. The XSL-FO Recommendation does not intend to expose all properties to
children of fo:external-graphic and fo:instream-foreign-object, but does
intend to expose those that might be needed by processors of the content of
those objects.

There may be other options as well that I have not thought of. Please
provide any guidance that you can to clarify the intent here. If the correct
answer is #3, please consider adding the properties enumerated above to
those that "apply" to these two formatting objects. For the case of MathML
at least, I don't see a downside. If a MathML author wants to explicitly
control these properties (NOT inherit them), he can do so. There may be
other namespaces or applications where introducing the FO properties into
the content processing would be a form of pollution.  But preventing that
would seem to be the responsibility of either the FO processor or the
content processor, not so much the availability of the raw material (exposed
properties) itself.

I realize that adding such properties to fo:external-graphic is a bit
awkward at best. It certainly looks silly to apply these properties to a
JPEG image, for example. I also realize that this list of properties may not
be comprehensive for all possible needs of content in other namespaces.

Thank you in advance for your help.

Victor Mote
The FOray Project www.foray.org
Received on Friday, 24 August 2007 14:13:05 UTC

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