clef-sign

<xs:simpleType name="clef-sign">
  <xs:annotation>
    <xs:documentation>The clef-sign element represents the different clef symbols.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:string">
    <xs:enumeration value="G"/>
    <xs:enumeration value="F"/>
    <xs:enumeration value="C"/>
    <xs:enumeration value="percussion"/>
    <xs:enumeration value="TAB"/>
    <xs:enumeration value="none"/>
  </xs:restriction>
</xs:simpleType>