The 'enumeration' element specifies an exact value.

You can have more than one of these to specify different values.

The enumeration value must be an instance of the base type.

A status keyword enumeration:

<xs:simpleType name="Status">
   <xs:restriction base="xs:string">
      <xs:enumeration value="draft"/>
      <xs:enumeration value="last call"/>
      <xs:enumeration value="proposed recomendation"/>
      <xs:enumeration value="unknown"/>
   </xs:restriction>
</xs:simpleType>