<xs:simpleType name="harmony-type">
  <xs:annotation>
    <xs:documentation>The harmony-type type differentiates different types of harmonies when alternate harmonies are possible. Explicit harmonies have all note present in the music; implied have some notes missing but implied; alternate represents alternate analyses.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:token">
    <xs:enumeration value="explicit"/>
    <xs:enumeration value="implied"/>
    <xs:enumeration value="alternate"/>
  </xs:restriction>
</xs:simpleType>