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More about pointless things

From: Alessandro Triglia <sandro@mclink.it>
Date: Tue, 28 Oct 2003 17:11:10 -0500
To: "[Public XML Schema-DEV]" <xmlschema-dev@w3.org>
Message-ID: <001901c39da0$68843990$8b01a8c0@aldebaran>


Suppose a sequence particle (SPB) with min occurs=1 and max occurs=3 is a particle of a model group at some depth within a complex type definition B.

I can derive a new complex type definition D by restricting B.  Suppose that D is identical to B except that the new SPD in D (corresponding to SPB in B) has min occurs=1 and max occurs=2.  This is allowed.

However, if I set the new SPD in D to have min occurs=1 max occurs=1, SPD becomes a pointless sequence, and the restriction is illegal.  The particles of SPD (and their descendants) can longer match those of SPB because one level of the structure (of D) has collapsed.

This doesn't make any sense to me.  I know of other similar cases where the "pointlessness" rules have weird effects.  Is there a plan to change the handling of pointlessness in version 1.1?

Alessandro Triglia
Received on Tuesday, 28 October 2003 17:12:44 UTC

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