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Re: Deriving from abstract types

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 19 Oct 2000 20:54:29 +0100
To: Gino Basso <GBasso@ware2.com>
Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Message-ID: <f5by9zk7gju.fsf@cogsci.ed.ac.uk>
Gino Basso <GBasso@ware2.com> writes:

> Basically it sounds like you're saying that the type 'ObjectName' is just an
> alias for the type 'anyType'. And since all types ultimately derive from
> 'anyType' this means any element can be substituted for the element
> 'objectName'.  My hope was that 'anotherName' would not be allowed to take
> part in the 'objectName' substitution group because it's type was not
> *strictly* derived from 'ObjectName'. This means that the abstract type
> 'ObjectName' does not really add any value to the schema other than to act
> as a more descriptive placeholder. Therefore it could just as easily be
> replaced with 'anyType' directly. Correct?

No, on two counts.  You can't restrict derivation from anyType, it's
there already.  But you _can_ restrict derivation from ObjectName, and 
you did, so a type derived by extension from ObjectName would _not_ be 
allowed.

Not sure what you mean by 'strictly' derived, anyway.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Thursday, 19 October 2000 15:54:32 UTC

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