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Re: complexType derivation method

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 10 Jan 2002 09:54:46 +0000
To: Eddie Robertsson <eddie@allette.com.au>
Cc: boriero <aboriero@hoc.elet.polimi.it>, XSD <xmlschema-dev@w3.org>
Message-ID: <f5by9j64jkp.fsf@cogsci.ed.ac.uk>
Eddie Robertsson <eddie@allette.com.au> writes:

> boriero wrote:
> >      Can I create a new complexType with a simpleContent by
> >      restricting or extending a basetype which is itself derived by
> >      restriction or extension ?


I don't disagree with any of Eddie's comments on what is and isn't
correct in boriero's first set of examples, but wrt

> As I read the spec this [type named '3'] should also be valid
> although none of the validators I tested with could validate this
> type correctly.

I demur -- XSV is happy with the attached, which is 1, 2 and 3 with
minor typos and the 'mixed' bug fixed.

> >     2.    when i create a new complexType with a complexContent , can
> > i restrict a base type removing one or more child elements?

> > <xs:complexType name="...">
> >     <xs:simpleContent>
> >         <xs:restriction base="..." >
> >             <xs:simpleType name="...">
> This is not valid as you have written it. The reason being that you
> can't declare a named simpleType that isn't a direct child of the
> xs:schema element. Written like this:
> <xs:complexType name="...">
>    <xs:simpleContent>
>       <xs:restriction base="..." >
>          <xs:simpleType>
>             <xs:restriction base="xs:integer"/>
> It could be used to restrict the text content of a previously defined
> complexType. However, there is a contradiction in the spec regarding
> this issue, see Henry's mail earlier [2].

That contradiction only arises if you're trying to restrict a complex
type definition with complex content.  If the complex type definition
has _simple_ content, then there's no doubt you're OK, so e.g. given
boriero's original example, corrected slightly, we can have:

<xs:complexType name="t1">
        <xs:extension base="xs:string">                     
            <xs:attribute name="x" type="xs:integer"/>      

<xs:complexType name="t4">                    
      <xs:restriction base="t1" >             
            <xs:restriction base="xs:token">
             <xs:pattern value=".*a.*"/>


> [1] http://www.w3.org/TR/xmlschema-1/#declare-type (in the table with
> heading: Complex Type Definition with simple content Schema Component)
> [2] http://lists.w3.org/Archives/Public/xmlschema-dev/2002Jan/0063.html

  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/

Received on Thursday, 10 January 2002 04:54:51 UTC

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