You must first create a simple type which represents the restricted simple
content:

<xs:simpleType name="mySimpleType>
    <xs:restriction base="xs:token">
              <xs:enumeration value="none" />
              <xs:enumeration value="hidden" />
              <xs:enumeration value="top" />
              <xs:enumeration value="bottom" />
   </xs:restriction>
</xs:simpleType>

then you should create and complex type and extend that simple content and
add an attribute:

<xs:complexType name="type_errors">
     <xs:simpleContent>
         <xs:extension base="mySimpleType">
              <xs:attribute name="stack" type="type__on_off" use="optional"
default="off" />
         </xs:extension>
     </xs:simpleContent>
</xs:complexType>
</xs:schema>

Thanks.


"Lüpher Cypher" <lupher.cypher@v...> wrote in message
news:im3uf.3254$tJ1.916@trndny01...
> Hi,
> I need to define an element which can take on predefined values and has
> an optional attribute.
>
> <xs:simpleType name="type__on_off">
>      <xs:restriction base="xs:token">
>          <xs:enumeration value="on" />
>          <xs:enumeration value="off" />
>      </xs:restriction>
> </xs:simpleType>
>
> <xs:complexType name="type_errors">
>      <xs:simpleContent>
>          <xs:restriction base="xs:token">
>              <xs:enumeration value="none" />
>              <xs:enumeration value="hidden" />
>              <xs:enumeration value="top" />
>              <xs:enumeration value="bottom" />
>              <xs:attribute name="stack" type="type__on_off"
> use="optional" default="off" />
>          </xs:restriction>
>      </xs:simpleContent>
> </xs:complexType>
>
> This gives me a validation error "XMLSchema:string is used as a base for
> complex type restriction".
>
> What am I doing wrong?
>
> Thanks!
>
>
> -- 
>
> - lüpher
> ---------------------------------------------
> "Man sieht nur das, was man weiß" (Goethe)