Re: Accepting non-deterministic content models

[Eric van der Vlist <vdv@dyomedea.com>]

"Roger L. Costello" wrote:
> 
> Hi Folks,
> 
> The following element, test, has a non-deterministic content model:

Maybe a stupid question, but (without discussing if it's a valid schema
or not) why is this non-deterministic with these numbers of occurrences
?

I would say that this allows either a, b or ab and that's it.

Eric
 
> <xsd:element name="test">
>     <xsd:complexType>
>         <xsd:choice>
>             <xsd:element name="a" type="xsd:string"/>
>             <xsd:element name="b" type="xsd:string"/>
>             <xsd:sequence>
>                <xsd:element name="a" type="xsd:string"/>
>                <xsd:element name="b" type="xsd:string"/>
>             </xsd:sequence>
>         </xsd:choice>
>     </xsd:complexType>
> </xsd:element>
> 
> XML Spy 4.0b, xerces 1.4.1 both accept this as valid.
> 
> xsv, turbo XML 2.2, and the IBM SQL all generate an error, indicating
> that the element, test, has a non-deterministic content model.
> 
> Isn't this a bad thing - some parsers accepting non-deterministic
> content models, while other parsers rejecting it?
> 
> I believe that the origin of this "problem" is that in the XML spec it
> states that parsers *should* reject non-deterministic content models.  I
> am wondering if perhaps "should" would be better replaced with "must"?
> /Roger
> 
-- 
See you at XTech in San Diego.
             http://conferences.oreillynet.com/cs/os2001/view/e_spkr/790
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
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