I need to put a restriction onto an attribute of "yes or no" - but not too sure of how to structure it - I'm trying the below but not sure how right or wrong it is: (advice would be appreciated) thanks
<xs:element name="DistinctiveMarks">
<xs:ComplexType>
<xs:SimpleContent>
<xs:extension base="xs:string">
<xs:attribute name="present" type="xs:string">
<xs:restriction base="xs:string">
<xs:pattern value="yes|no"/>
</xs:restriction>
</xs:attribute>
</xs:extension>
</xs:SimpleContent>
</xs:ComplexType>
</xs:element>