<xs:simpleType name="volumeType">
  <xs:annotation>
    <xs:documentation>The volume units (can be cubic_meters, cubic_us_feet, cubic_int_feet, cubic_us_feet_inches, cubic_int_feet_inches, cubic_us_chains, cubic_int_chains, cubic_mile, cubic_int_inches, cubic_us_inches, cubic_millimeters, cubic_centimeters, cubic_kilometers, cubic_int_yards or cubic_us_yards)</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:NMTOKEN">
    <xs:enumeration value="cubic_meters"/>
    <xs:enumeration value="cubic_us_feet"/>
    <xs:enumeration value="cubic_int_feet"/>
    <xs:enumeration value="cubic_us_feet_inches"/>
    <xs:enumeration value="cubic_int_feet_inches"/>
    <xs:enumeration value="cubic_us_chains"/>
    <xs:enumeration value="cubic_int_chains"/>
    <xs:enumeration value="cubic_mile"/>
    <xs:enumeration value="cubic_int_inches"/>
    <xs:enumeration value="cubic_us_inches"/>
    <xs:enumeration value="cubic_millimeters"/>
    <xs:enumeration value="cubic_centimeters"/>
    <xs:enumeration value="cubic_kilometers"/>
    <xs:enumeration value="cubic_int_yards"/>
    <xs:enumeration value="cubic_us_yards"/>
  </xs:restriction>
</xs:simpleType>