XML Schema restriction contradiction?

[Lyndon J B Nixon <nixon@fokus.gmd.de>]

hi,

is the current definition of <restriction> in the XML Schema CR
24/10/2001 contradictory or am i missing something?

in Part 1:Structures Appendix A: Schema for XML Schemas (normative)

<complexType name="restrictionType">

        

<complexContent>

        

        

<extension
base="annotated">

        

        

        

<sequence>

        

        

        

        

<choice>

        

        

        

        

        

<group
ref="typeDefParticle" minOccurs="0"/>

        

        

        

        

        

<group
ref="simpleRestrictionModel" minOccurs="0"/>

        

        

        

        

</choice>

        

        

        

<group
ref="attrDecls"/>

        

        

        

</sequence>

        

        

<attribute
name="base" type="QName"
use="required"/>

        

        

</extension>

        

</complexContent>
</complexType>

This seems to conform to the Schema validation that I am using (XML Spy
3.5) which returns an error that the base attribute is required
when i use a XML Schema containing restrictions without a base but with a
simpleType child.

However in Part 2:Datatypes section 5.1.1

"Either the base  [attribute] or the simpleType  [child]
must be present, but not both."

which matches with the given Schema for Datatype Definitions which
states

<element name="restriction"
substitutionGroup="simpleDerivation"
id="restriction">

        

<complexType>

        

        

<annotation>

        

        

        

<documentation
xml:lang="en"
source="http://www.w3.org/TR/xmlschema-2/#element-restriction">

      

        

base
attribute and simpleType child are mutually exclusive, but one or other
is required

       

        

        

</documentation>

        

        

</annotation>

       

        

<complexContent>

        

        

        

<extension
base="annotated">

        

        

        

        

<group
ref="simpleRestrictionModel"/>

        

        

        

        

<attribute
name="base" type="QName"
use="optional"/>

        

        

        

</extension>

        

        

</complexContent>

        

</complexType>
</element>

So, is the base attribute optional or required? Is the XML Spy
validator correctly validating my XML Schema?
The offending (error producing) XML Schema code is:

<simpleType
name="SFColor">
      <restriction>
         <simpleType>
           
<list itemType="xmta:ZeroToOneFloat"/>
         
</simpleType>
         <length
value="3"/>
      </restriction>
   </simpleType>

regards

lyndon

Lyndon J B Nixon ... MAGIC Centre, GMD FOKUS ... Berlin, Germany
"what is now proved was once only imagined" - william blake
PhD Student, Integration of Internet into MPEG-4 & MPEG-7
nixon@fokus.gmd.de   members.tripod.co.uk/~madeejit/phd.htm