Re: References to a value of an element in another element?

--- Pete Cordell <petexmldev@tech-know-ware.com> wrote:

> Original Message From: "Carl Eric Codere"
> > Greetings,
> >         I have a simple question, but i am not sure it is possible to
> > represent  it in XMLSchema, if so any help would be really appreciated.
> >
> > I have variable-length structure and the length of the 2nd element
> depends 
> > on
> > the value of the first element. How is it possible to specify this in
> > XMLSchema?
> >
> > <xsd:complexType name="Chunk">
> >    <xsd:sequence>
> >      <xsd:element name="size"   type="xsd:integer"/>
> >      <xsd:element name="data"  type="xsd:hexBinary" ?????/>
> >    </xsd:sequence>
> >  </xsd:complexType>
> >
> > The problem is with element "data", how do i specify that its length is 
> > the
> > value "size"???
> 
> I'm afraid this is not possible in XML Schema alone.  Including additional 
> Schematron constraints may be able to help.
> 
> (FWIW - XSD 1.1, that is currently being developed, supports co-constraints
> such as this.  But I'm not sure it would support the type of co-constraint 
> that you require here.)

Greetings,
          What is the section in XML Schema 1.1 draft that explains this
feature? If this feature is not currently possible in XML Schema, what would
syntax would you suggest?

My goal here is to be able to describe binary file formats using XML Schema,
or any other scheman language (such as ASN.1, does ASN.1 this then?)...

Any help would be appreciated...
Carl



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