Units

<xs:simpleType name="Units">
  <xs:annotation>
    <xs:documentation>Enumeration of unit scheme used. Only SI or Physiological units allowed</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:string">
    <xs:enumeration value="Physiological Units">
      <xs:annotation>
        <xs:documentation>Milisecond, millivolt, centimeter, etc</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="SI Units">
      <xs:annotation>
        <xs:documentation>Second, volt, meter, etc.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
  </xs:restriction>
</xs:simpleType>