<xs:simpleType name="ReferenceFeatureAssociationSpecificationParameterEnumType">
  <xs:annotation>
    <xs:documentation>The ReferenceFeatureAssociationSpecificationParameterEnumType enumerates values that describe ISO specific filter modifying parameters. P = peak V = valley T = peak to valley Q = root mean square (RMS)</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:NMTOKEN">
    <xs:enumeration value="P"/>
    <xs:enumeration value="V"/>
    <xs:enumeration value="T"/>
    <xs:enumeration value="Q"/>
  </xs:restriction>
</xs:simpleType>