[relaxng-user] association of RELAX NG with a document

[James Clark]

On Thu, 2003-10-23 at 20:43, Daniel Veillard wrote:

> the idea growing up seems to have the association done at the toolkit
> level instead of having it into the instance.

Right. I believe it's quite wrong for a schema language to dictate that
a document type designer must use an element name or an attribute for a
particular purpose (as W3C XML Schema does with xsi:type or
xsi:schemaLocation). The document type designer should be the one who
decides what element names and attribute names to use, and the schema
language should allow the document type designer to write a schema to
reflect their decision.  I think this extends to any association
mechanism and it also applies to processing instruction target names.

This does not prevent your having something in the instance that
influences the association but it does imply that the ultimate authority
must be outside the instance.  If, for example, you want a processing
instruction in the instance to point to the schema, then there must be
something outside the instance that says that this is what you want and
that specifies the processing instruction target to use for this
purpose.

Once you decide that you want something outside the instance to control
the association, I think it's an obvious decision to express that
something in XML and it's highly desirable to make it
application-independent. 

> It's unclear
> to me whether the approach taken by nXML can really be expanded to other
> frameworks

If it can't, then it's a bug.  It was a fundamental design goal to
express the association rules in an application-independent way.
Eventually, I hope to implement this for Jing as well.

James