Additional NDR Rules

[Chin Chee-Kai <cheekai@softml.net>]

These are some that I can summarise now.  Please consider
incorporating them.

Thanks.


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CK-1.    Unless otherwise stated, all elements SHOULD be 
declared qualified, and all attributes SHOULD be declared
unqualified.  This can be implemented conveniently by
setting the schema attributes elementFormDefault="qualified"
and attributeFormDefault="unqualified".


CK-2.    The local names "DerivedCode" and "DerivedCodeType"
are strictly reserved for code list implementations, and
MUST NOT be used in any other context.



CK-3.   [Replace the two-level schema import rule with:]

Schema SHOULD import other schemas only when the imported
schemas' contents are used in the importing schema.
Schema import MUST avoid circular imports that result in
loading the same schema more than once.


<!--
Note: it is not non-compliant with XML Schema spec to
import the same schema more than once, provided the semantic
treatment result in exactly the same as if the schema had
been loaded the first time.  But we should rule this more
lenient (but not incorrect) spec out in UBL.
-->

<!--
Note 2: The two-level import restriction has turned out
to be too restrictive for implementation.  It needs to
be relaxed.  An example wording is proposed above.
-->


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Best Regards,
Chin Chee-Kai
SoftML
Tel: +65-6820-2979
Fax: +65-6743-7875
Email: cheekai@SoftML.Net
http://SoftML.Net/