As the base type declared inside the type:
<xs:simpleType name="uri"> <xs:restriction> <xs:simpleType> <xs:restriction base="xs:anyURI"> <xs:pattern name="\w+:.*"/> </xs:restriction> </xs:simpleType> <xs:enumeration value="http://cde.berkeley.edu/"> <xs:enumeration value="http://sims.berkeley.edu/"> </xs:restriction> </xs:simpleType>
Why you would ever want to do this...
...maybe it is there for completeness: "everywhere you can refer to a type you can give an explicit definition of that type instead"