<simpleType name="RegistryStatusEnumType">
  <annotation>
    <documentation>Lifecycle states of a registered specification. Closed, because the three states are exhaustive: a standard is current, replaced by a named successor, or retired without one.</documentation>
  </annotation>
  <restriction base="string">
    <enumeration value="active">
      <annotation>
        <documentation>Current and in force. The default reading when registryStatus is absent.</documentation>
      </annotation>
    </enumeration>
    <enumeration value="superseded">
      <annotation>
        <documentation>Replaced by a later standard, which should be named in supersededByRef. The entry is retained so existing citations keep resolving.</documentation>
      </annotation>
    </enumeration>
    <enumeration value="withdrawn">
      <annotation>
        <documentation>Withdrawn by its publisher without a direct replacement. Retained for the same reason: instances published while it was current still cite it.</documentation>
      </annotation>
    </enumeration>
  </restriction>
</simpleType>