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Re: Ambiguous Content Models

• To: "'xml-dev@l...'" <xml-dev@l...>
• Subject: Re: Ambiguous Content Models
• From: Eric van der Vlist <vdv@d...>
• Date: Fri, 03 Oct 2003 12:57:41 +0200
• In-reply-to: <3F7D5299.2050108@m...>
• Organization: Dyomedea (http://dyomedea.com)
• References: <3F7D5299.2050108@m...>

On Fri, 2003-10-03 at 12:42, Max Chappell wrote:

> Does anybody have any comments on the validity of the above? 

The IBM Schema Quality Checker is right...

If you have several "Person" elements in your instance document, a
schema processor can't immediately tell if they belongs to the first
sequence, to the xs:element that follows or to the second sequence and
that's violating the restrictions of W3C XML Schema.

Furthermore, your schema is not capturing "they want any element of the
three elements in any order, as many or as few times as they want" :-)
...

The usual way to translate "any element of the three elements in any
order, as many or as few times as they want" in WXS is through
xs:choice:

    <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:group ref="tns:GenericElements"/>
        <xs:element name="Person" type="tns:Person"/>
        <xs:element name="Location" type="tns:Loc"/>
    </xs:choice>

That doesn't capture the fact that "they also want at least one 
person element to be present every time" but I don't see how you can
capture this using WXS alone.

Hope this helps.

Eric
-- 
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
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