XSchema Spec Section 2.2, Draft 1

Simon St.Laurent SimonStL at classic.msn.com
Thu Jun 11 01:53:10 BST 1998

Ron Bourret writes:
>This is a mistake in the current DTD, where we use id attributes for both 
>ElementDecl and Notation (but not AttDef).  It's not quite clear to me if 
>notations are in or out at the moment.  If they stay in, we could retain an 
>ID attribute on ElementDecls and get uniqueness checking from validating 
>parsers for free.  On the other hand, because a validator is looking like a 
>reasonable application to build, there seems no reason to do this, since the 
>validator would need to check uniqueness for non-validating parsers anyway.
>Note also that attribute names are required to be unique only within the 
>attributes of a single element, not all attributes.

It's not quite clear to me either whether NOTATION is in or out, though it 
does have a place in the current outline.  If NOTATION is in, ID attributes 
should not be used for both types of declarations.

We need to define behavior for the verifier (my term for validator, since I 
don't want to get twisted in DTDs).  The verifier could check that all element 
names are unique, or it could accept the first or last element declaration 
made.  Allowing repeated declarations - which override would make it easier to 
combine XSchemas, but could also create a mess.  (Attributes? Content models?) 
Whatever we decide, the verifier is going to have some work to do.  

I would like to be able to build XSchema applications on top of non-validating 
parsers - dealing with validation as well as XSchemas seems like a lot of 
redundant effort to me.  I don't think we gain that much from using ID.

Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer / Cookies

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