<simpleType name="TimeUnitType">
  <annotation>
    <documentation xml:lang="en">Standard units for measuring time intervals (see ISO 31-1).</documentation>
  </annotation>
  <union>
    <simpleType>
      <restriction base="string">
        <enumeration value="year"/>
        <enumeration value="day"/>
        <enumeration value="hour"/>
        <enumeration value="minute"/>
        <enumeration value="second"/>
      </restriction>
    </simpleType>
    <simpleType>
      <restriction base="string">
        <pattern value="other:\w{2,}"/>
      </restriction>
    </simpleType>
  </union>
</simpleType>