Further info on validation issue

[rjelliffe at allette.com.au]

1) The validator I was using is the MSXML validator (I think the 2009
version of MSXML 4) *not* Xerces, apologies.


2) The problem is one of circular imports.

For example, when I try to validate dml-lockedCanvas.xsd I get the error
 "Duplicate element declaration with the name
"{http://purl.oclc.org/ooxml/drawingml/lockedCanvas}lockedCanvas"

dml-lockedCanvas.xsd has
 	<xsd:import namespace="http://purl.oclc.org/ooxml/drawingml/main"
schemaLocation="dml-main.xsd"/>

dml-main.xsd has
	<xsd:import namespace="http://purl.oclc.org/ooxml/drawingml/lockedCanvas"
schemaLocation="dml-lockedCanvas.xsd"/>


3) XSD allows circular imports. XSD has the strange note on this at s4.2.3
"Note: The above is carefully worded so that multiple <import>ing of the
same schema document will not constitute a violation of clause 2 of [],
but applications are allowed, indeed encouraged, to avoid <import>ing the
same schema document more than once to forestall the necessity of
establishing identity component by component. Given that the
schemaLocation [attribute] is only a hint, it is open to applications to
ignore all but the first <import> for a given namespace, regardless of the
·actual value· of schemaLocation, but such a strategy risks missing useful
information when new schemaLocations are offered."


4) However XSD tools are notoriously buggy in this regard. I had thought
that removing circular imports was one of the goals for the revised
schemas.


5) The BRM adopted JP-02 as resolution 39:

39.    Multiple schema processors        [Japan] JP-02(R-344)
XML schemas are used by XML parsers for validating the structure and
content of XML files using the matching data model.  The Open XML
reference schemas were fully compatible with the W3C XSD schema standard;
however, the implementations of XML parsers have varying levels of XSD
standard conformance.  Japan discovered during testing that these schemas
were not processible by the Apache Xerces-J and Sun's MSV validators
because of a module importation problem.  Ecma agreed that supporting the
broadest range of development and testing tools is an important priority
and therefore modified the Office XML schemas to be compatible with many
validators including the 2 previously cited by Japan. The updated Ecma
schemas were adopted. Approved.
http://blogs.msdn.com/brian_jones/archive/2008/03/15/narrative-of-the-iso-iec-dis-29500-brm-meeting.aspx

Since this relates to a Japanese BRM issue, I am happy to defer to
Murata-san's judgement on all aspects.

Cheers
Rick Jelliffe