XSD Definition for Enumerated Value
This solution worked for me:
<xs:element name="color">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="green"/>
<xs:enumeration value="red"/>
<xs:enumeration value="blue"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
You can define an enumeration within the context of a simpleType.
<xs:simpleType name="color" final="restriction" >
<xs:restriction base="xs:string">
<xs:enumeration value="green" />
<xs:enumeration value="red" />
<xs:enumeration value="blue" />
</xs:restriction>
</xs:simpleType>
<xs:element name="SomeElement">
<xs:complexType>
<xs:sequence>
<xs:element name="Color" type="color" />
</xs:sequence>
</xs:complexType>
</xs:element>