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RE: Occurrence constraints

From: Xan Gregg <Xan.Gregg@jmp.com>
Date: Thu, 3 Jun 2004 13:02:10 -0400
Message-ID: <1F145982392D6143BCF3CC670E4C7FA02710AB@MERC27.na.sas.com>
To: "Keith Suderman" <keith@suderman.com>, <xmlschema-dev@w3.org>

The last clause of the following constraint rules out having 
both minOccurs="0" and maxOccurs="0" specified:

  Schema Component Constraint: Particle Correct
  All of the following must be true:
  1 The values of the properties of a particle must be as described
   in the property tableau in The Particle Schema Component (3.9.1),
   modulo the impact of Missing Sub-components (5.3).
  2 If {max occurs} is not unbounded, that is, it has a numeric value,
   then all of the following must be true:
  2.1 {min occurs} must not be greater than {max occurs}.
  2.2 {max occurs} must be greater than or equal to 1. 

On the other hand, there are also multiple parenthetical comments, such as 

  (unless minOccurs=maxOccurs=0, in which case the item
  corresponds to no component at all)

But I think the constraint dominates.

I don't know of a better solution to your second issue.

xan

-----Original Message-----
From:Keith Suderman
Sent: Thursday, May 27, 2004 4:44 AM
Subject: Occurrence constraints

Two quick questions.

1. Is it legal to have both minOccurs="0" and maxOccurs="0" specified for 
an element?

2. What is the best way to define SGML SDATA entities (i.e. eacute) for an 
XML document using XML Schema?  Currently I am using the DOCTYPE to specify 
an "empty" DTD that does nothing but define the entities and a schema for 
the document structure.  However, some XML parsers do not like this 
approach.  Is there a better way of going about this?

Thanks in advance.
Keith
Received on Thursday, 3 June 2004 13:02:12 GMT

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