Re: Logical relationships between documents and schemata: was Re:using namespaces to version

[Jonathan Borden <jborden@mediaone.net>]

Tony Coates wrote:

>
> Unfortunately, the application requirement I was alluding to is
> Restriction(Snew,Sapp), which is equivalent to Extension(Sapp,Snew)
> (from what I understand of your algebra at "
> http://www.rddl.org/SchemaAlgebra.html").  So, the problem remains, but
> hopefully more clearly expressed now.

ok. so when Extension(Snew,Sold) it is 'safe' to substitute the new schema
Snew as the primary scheme (e.g. purpose=
http://www.rddl.org/purposes#schema-validation) in the namespace.

on the other hand when Restriction(Snew,Sold) doing this will 'invalidate'
previously happy documents. Two options are:

1) use a new namespace

2) use something like xsi:schemaLocation to reference the proper schema for
this particular instance document

of course (2) is specific to XML Schema, and supposing the same facility is
needed for other schemata e.g. Schematron, TREX we might invent a similar
instance attribute:

rddl:schemaPurpose="..." which generally defaults to
http://www.rddl.org/purposes#schema-validation but could allow selection of
a set of schemata all sharing the same purpose (and this purpose URI is then
used to perform versioning).

btw: thanks for your useful comments and corrections on the schema algebra

>
>      Cheers,
>           Tony.

- Jonathan