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Section 8.5 clarification

From: FABLET Youenn <Youenn.Fablet@crf.canon.fr>
Date: Wed, 3 Mar 2010 19:20:51 +0100
To: "public-exi-comments@w3.org" <public-exi-comments@w3.org>
Message-ID: <52D873DC3403944C840CF3063ABE43A719044F85@Nina.crf.canon.fr>
Dear all,

Section 3 states that:
"The built-in EXI grammars accept any XML document or fragment and may be augmented with productions derived from XML Schemas [XML Schema Structures]<http://www.w3.org/TR/exi/#schema1>   [XML Schema Datatypes]<http://www.w3.org/TR/exi/#schema2>, RELAX NG schemas [ISO/IEC 19757-2:2003]<http://www.w3.org/TR/exi/#relaxng>, DTDs [XML 1.0]<http://www.w3.org/TR/exi/#XML10>   [XML 1.1]<http://www.w3.org/TR/exi/#XML11> or other sources of information";
Section 5.4 states that :
"Section 8.5 Schema-informed Grammars<http://www.w3.org/TR/exi/#informedGrammars> describes the system to derive schema-informed grammars from XML Schemas."
Section 8.5 states that:
"This section describes the schema-informed grammars used by EXI when schema information is available to describe the contents of the EXI stream<http://www.w3.org/TR/exi/#key-existream>. Schema information used for processing an EXI stream is either indicated by the header option schemaID<http://www.w3.org/TR/exi/#key-schemaIDOption>, or communicated out-of-band in the absence of schemaID<http://www.w3.org/TR/exi/#key-schemaIDOption>. Schema-informed grammars are independent of any particular schema language and can be derived from XML Schemas [XML Schema Structures]<http://www.w3.org/TR/exi/#schema1>   [XML Schema Datatypes]<http://www.w3.org/TR/exi/#schema2>, RELAX NG schemas [ISO/IEC 19757-2:2003]<http://www.w3.org/TR/exi/#relaxng>, DTDs [XML 1.0]<http://www.w3.org/TR/exi/#XML10>   [XML 1.1]<http://www.w3.org/TR/exi/#XML11> or other schema languages for describing what is likely to occur in an EXI stream. "

The exact meaning of these three sentences are somehow unclear when put together.
In particular it is easy to infer from the start of section 8.5 that this section defines a mapping from several languages (XSD, RNG, DTD...), which is not the case since the mapping is restricted to XSD only. On the contrary, section 5.4 seems to induce that only XSD is supported currently (?).

It would be nice that, at a high level, the specification clearly states the following two points:

-          This specification defines schema informed grammars that are schema-neutral

-          This specification defines one mapping to schema informed grammars, the input being XSD.
Of course, the specification is free to state that other mappings can be done.

The additional related comment I have is that section 8.5 defines both what are schema-informed grammars and how to generate them from XSD.
The definition of the schema-informed grammars is tightly linked in the spec to XSD words and concepts like GED for instance.
This is perfectly fine to me. However, to create another mapping, one would need to rewrite something similar to the whole section 8.5.
Therefore the sentence quoted from section 8.5 could be clarified with that respect.

Regards,
                Youenn
Received on Wednesday, 3 March 2010 18:21:27 UTC

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