Kind of pseudo code.  I filed up the issue in a private group, and hope that 
corrected as fast as possible.

"Mahalax" <Mahalax@d...> wrote in message 
news:45CD06ED-771E-45FF-A045-3E2FB5DED9BD@m......
> Would you pls explain what you mean be tokenized... Using Complextype 
> instead
> of Attributegroup works.
>
> -Maha.
>
> "Han" wrote:
>
>> Nice. The example seems to be tokenized one. Anyway, can be misleading.
>> Simply replace the <attributeGroud> with <complexType>. This seems to 
>> work
>> for me.
>>
>> <xs:schema
>>  xmlns:xs="http://www.w3.org/2001/XMLSchema"
>>  elementFormDefault="qualified"
>> >
>>
>> <xs:complexType name="A">
>>   <xs:attribute name="x"/>
>>   <xs:attribute name="y"/>
>>  </xs:complexType>
>>
>> <xs:complexType name="B">
>>   <xs:complexContent>
>>    <xs:restriction base="A">
>>     <xs:attribute name="x" use="required" />
>>     <xs:attribute name="y" use="prohibited"/>
>>    </xs:restriction>
>>   </xs:complexContent>
>>  </xs:complexType>
>>
>> <xs:element name='a' type='B'/>
>>
>> </xs:schema>
>>
>> "Mahalax" <Mahalax@d...> wrote in message
>> news:2E16A199-7E18-4CA8-999F-FCE336D365C8@m......
>> > Here is the link:
>> >
>> > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/xmlsdk/html/xsdrefattributeelement.asp
>> >
>> > "Han" wrote:
>> >
>> >> Interesting example. As I read MSDN, only the name of a complexType is
>> >> allowed.
>> >>
>> >> (Excerpt)
>> >>
>> >> restriction (complexContent)
>> >>
>> >> base
>> >> The name of a complexType element defined in this schema (or another
>> >> schema
>> >> indicated by the specified namespace). The element containing the
>> >> restriction element is derived from the type specified by the base 
>> >> value.
>> >>
>> >> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/xmlsdk/html/xsdrefrestrictioncomplexContentElement.asp
>> >>
>> >> Do you happened to have a link of the example?
>> >>
>> >> "Mahalax" <Mahalax@d...> wrote in message
>> >> news:796D6E29-A336-48B7-92B9-CA8C6F73F8CD@m......
>> >> > Yes, it does. Here is the MSDN sample.
>> >> >
>> >> > <xs:attributeGroup name="A">
>> >> >  <xs:attribute name="x" type="xs:NCName"/>
>> >> >  <xs:attribute name="y" type="xs:QName"/>
>> >> > </xs:attributeGroup>
>> >> >
>> >> > <xs:complexType name="B">
>> >> >  <xs:complexContent>
>> >> >   <xs:restriction base="xs:A">
>> >> >    <xs:attribute name="x" use="required" />
>> >> >    <xs:attribute name="y" use="prohibited"/>
>> >> >   </xs:restriction>
>> >> >  </xs:complexContent>
>> >> > </xs:complexType>
>> >> >
>> >> > -Maha
>> >> >
>> >> > "Han" wrote:
>> >> >
>> >> >> I mean reuse. I mean @use attribute at reused attributeGroup.
>> >> >> By the way, does MSDN example use name of an attributeGroup for its
>> >> >> @base
>> >> >> attribute?
>> >> >>
>> >> >> "Mahalax" <Mahalax@d...> wrote in message
>> >> >> news:CE54F817-01C7-487C-B277-F8245F2E0531@m......
>> >> >> > Hi Han,
>> >> >> >
>> >> >> > Actually I am trying to explore the attributegroup and its 
>> >> >> > purpose.
>> >> >> > Many
>> >> >> > of
>> >> >> > my schemas have a set of common atributes which I am trying to
>> >> >> > declare
>> >> >> > commonly and reuse as required. The code I have posted is an
>> >> >> > adaptation
>> >> >> > from
>> >> >> > MSDN which is not working.
>> >> >> >
>> >> >> > "Han" wrote:
>> >> >> >
>> >> >> >> OOPS, I mean @use by @required in the earlier post. Values are,
>> >> >> >>
>> >> >> >> optional, prohibited, required
>> >> >> >>
>> >> >> >> "Mahalax" <Mahalax@d...> wrote in message
>> >> >> >> news:207B477E-4686-4015-8CFE-A510B3AEBE6B@m......
>> >> >> >> > Greetings.
>> >> >> >> >
>> >> >> >> > Below is the schema snippet I am trying to explore
>> >> >> >> > attributegroups
>> >> >> >> > and
>> >> >> >> > attribute's use property. However I am getting a validation 
>> >> >> >> > error
>> >> >> >> > saying
>> >> >> >> > "undefined value for base encountered", pointing to
>> >> >> >> > <xs:restriction>.
>> >> >> >> > Please
>> >> >> >> > help.
>> >> >> >> >
>> >> >> >> > <?xml version="1.0" encoding="UTF-8"?>
>> >> >> >> > <xs:schema elementFormDefault="qualified"
>> >> >> >> > attributeFormDefault="unqualified"
>> >> >> >> > xmlns:xs="http://www.w3.org/2001/XMLSchema">
>> >> >> >> > <xs:attributeGroup name="grp">
>> >> >> >> > <xs:attribute name="x" type="xs:string"/>
>> >> >> >> > <xs:attribute name="y" type="xs:string"/>
>> >> >> >> > <xs:attribute name="z" type="xs:string"/>
>> >> >> >> > </xs:attributeGroup>
>> >> >> >> > <xs:complexType name="A">
>> >> >> >> > <xs:complexContent>
>> >> >> >> > <xs:restriction base="xs:grp">
>> >> >> >> > <xs:attribute name="x" use="required"/>
>> >> >> >> > <xs:attribute name="y" use="prohibited"/>
>> >> >> >> > <xs:attribute name="z" use="required"/>
>> >> >> >> > </xs:restriction>
>> >> >> >> > </xs:complexContent>
>> >> >> >> > </xs:complexType>
>> >> >> >> > </xs:schema>
>> >> >> >> >
>> >> >> >> > Best Regards,
>> >> >> >> > Mahalakshmi Natarajan
>> >> >> >> > http://mahalax.blogspot.com
>> >> >> >> > http://dotnetjunkies.com/weblog/mahalax
>> >> >> >>
>> >> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
>>
>>