[w3c sml] [4684] sml:keyref reference to xs:key/unique



This email will service to start the discussion of 4684 regarding
whether sml:keyref should be able to reference xs:key/unique elements.
I must admit that I took this bugzilla because the basic idea presented
in the following paragraph rather interested me.  However, assessing
this idea turned out to be a tremendous undertaking because I don't
understand enough about the background structures being maintained in
the PSVI.


This is an issue undoubtedly because the current SML spec is silent on
whether sml:keyref can refer to xs:key/unique elements.   I would assert
that there is a powerful reason for allowing this: namely, to allow SML
models to be built from existing models that already have xs:key/unique
structures defined for the elements that need to referenced in the SML
model.  Inter-document references could utilize identity constraints
over existing keys in the referenced documents based on existing keys.
Therefore, I believe that issue here is whether there is anything in XML
Schema preventing this kind of identity constraint.


The issue, I believe focuses upon the XML Schema rule that the refer
attribute of xs:keyref should refer to a xs:key/unique element defined
under the same element or under one of that element's children.
Presumably this same rule holds for sml:keyref and sml:key/unique-at
least that is the way I understood an answer I was given when I raised
the question of whether sml ICs must comply with the same structural
restrictions as XSD ICs during the first F2F.  How these tables can
interrelated should be discussed within the WG.  On the other hand, the
refer attribute of sml:keyref is a QName and could presumably identify a
xs:key/unique in another namespace.


So, I hope this servers to instigate discussion!


Kirk Wilson, Ph.D.
CA Inc.
Research Staff Member, CA Labs
Intellectual Property and Standards
Council of Technical Excellence
W3C Advisory Committee Representative

Tele: + 1 603 823-7146
Fax:   + 1 603 823-7148


Received on Friday, 24 August 2007 19:09:11 UTC