unique attribute names for element nodes

Is there a way to specify the unique constraints on attribute names  
on element nodes?

For an example, see the following schema:
<xsd:element name="Category" minOccurs="0" maxOccurs="unbounded">
         <xsd:annotation>
                 <xsd:documentation>Logger Category</xsd:documentation>
         </xsd:annotation>
         <xsd:complexType>
                 <xsd:attribute name="Name" use="required"  
xdb:SQLType="VARCHAR"/>
                 <xsd:attribute name="Level" use="required"  
xdb:SQLType="INTEGER"/>
         </xsd:complexType>
</xsd:element>

And instance for the above schema can be something like this:
<Category Name="TestNode1" Level="DEBUG"/>
<Category Name="TestNode1" Level="INFO"/>
<Category Name="TestNode2" Level="FATAL"/>

My question is that the category name "TestNode1" has been repeated  
twice in the above example. So is there a way that we can specify in  
the XML Schema that only one unique value of the category name can be  
present in an instance instead of allowing multiple same category name.

Please exemplify.

Thanks !

Rajesh



-----------
Rajesh Seenichamy
RSeenichamy@CSC.COM
Rajesh.Seenichamy@gmail.com
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