<xs:simpleType name="notehead-value">
  <xs:annotation>
    <xs:documentation>The notehead type indicates shapes other than the open and closed ovals associated with note durations. The values do, re, mi, fa, so, la, and ti correspond to Aikin's 7-shape system. The arrow shapes differ from triangle and inverted triangle by being centered on the stem. Slashed and back slashed notes include both the normal notehead and a slash. The triangle shape has the tip of the triangle pointing up; the inverted triangle shape has the tip of the triangle pointing down.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:string">
    <xs:enumeration value="slash"/>
    <xs:enumeration value="triangle"/>
    <xs:enumeration value="diamond"/>
    <xs:enumeration value="square"/>
    <xs:enumeration value="cross"/>
    <xs:enumeration value="x"/>
    <xs:enumeration value="circle-x"/>
    <xs:enumeration value="inverted triangle"/>
    <xs:enumeration value="arrow down"/>
    <xs:enumeration value="arrow up"/>
    <xs:enumeration value="slashed"/>
    <xs:enumeration value="back slashed"/>
    <xs:enumeration value="normal"/>
    <xs:enumeration value="cluster"/>
    <xs:enumeration value="none"/>
    <xs:enumeration value="do"/>
    <xs:enumeration value="re"/>
    <xs:enumeration value="mi"/>
    <xs:enumeration value="fa"/>
    <xs:enumeration value="so"/>
    <xs:enumeration value="la"/>
    <xs:enumeration value="ti"/>
  </xs:restriction>
</xs:simpleType>