xs:attrribute with union type and fixed value

 
        I would like to ask whether it is right to have an schema
attribute definition which is of a union type and also contains a fixed
value in it declaration. 
 
 
For example
 
<xsd:attribute name="test" type="UnionType" fixed="010101010" />
 

This e-mail is confidential and privileged. If you are not the intended recipient please accept our apologies; please do not disclose, copy or distribute information in this e-mail or take any action in reliance on its contents: to do so is strictly prohibited and may be unlawful. Please inform us that this message has gone astray before deleting it. Thank you for your co-operation.