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allow unordered sequence

From: David Wright <dawright@microsoft.com>
Date: Thu, 06 Mar 2003 11:33:25 -0700
Message-Id: <>
To: W3C XML Schema Comments list <www-xml-schema-comments@w3.org>

This is a request for the next version of XML-Schema. Please allow a way to 
specify that an element may have various numbers of child elements in any 
order. For example:

<A> must contain&

0 or 1 <a/> s

exactly 1 <b/>

any number of <c/> s

             &in any order

(I have learned that it is actually possible to do this by implementing a 
decision tree using <xsd:choice> and <xsd:sequence>, and for this toy 
problem that isn t too bad. In my real-world scenario, though, I have 11 
child elements.)

I realize that, if one changes the schema so that <c/> s are contained 
within a <C> element and makes the <C> element a child of <A>, one can do 
this using <xsd:all>. Not all of us attempting to validate documents using 
XML-Schema, though, have the possibility of changing to schema used. We 
need to be able to express a rule that existed in someone s else s head, to 
whom it never occurred that the rule might some day need to be expressed in 

It may make implementations easier to require that like child elements 
occur together, e.g. that


is allowed, but


isn t. This would still be a great improvement.

A simple way to do this simple, at least, at the spec level -- is to relax 
the condition that, for child elements of <xsd:all>, minOccurs and 
maxOccurs can only be 0 or 1.
Received on Thursday, 6 March 2003 13:34:56 UTC

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