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[Bug 4617] SML Schema: The refer attribute in sml:keyref should be optional

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Date: Thu, 05 Jul 2007 14:21:09 +0000
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To: public-sml@w3.org
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http://www.w3.org/Bugs/Public/show_bug.cgi?id=4617





------- Comment #3 from sandygao@ca.ibm.com  2007-07-05 14:21 -------
If an element declaration E1 for the name "e" appears in a complex type D, who
is a restriction of B, and B also includes an element declaration E2 for "e",
then schema requires that E1's {identity constraints} is a superset of that of
E2. If one can't reuse identity constraints (by having a "ref" attribute), as
soon as B includes a local E2 with IDCs, it's not possible to restrict B.

Schema 1.0 had this problem, which makes restriction hard to use. Schema 1.1
will introduce an "ref" attribute on key/keyref/unique, so that E1 can now
reuse E2's identity constraints, to satisfy the constraint mentioned above.

The proposed change to SML was motivated by the schema 1.1 direction.
Received on Thursday, 5 July 2007 14:21:13 UTC

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