atom:KnownRelCodeType

<xs:simpleType name="KnownRelCodeType">
  <xs:restriction base="xs:string">
    <xs:enumeration value="alternate">
      <xs:annotation>
        <xs:documentation>The value "alternate" signifies that the IRI in the value of the href attribute identifies an alternate version of the resource described by the containing element.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="related">
      <xs:annotation>
        <xs:documentation>The value "related" signifies that the IRI in the value of the href attribute identifies a resource related to the resource described by the containing element. For example, the feed for a site that discusses the performance of the search engine at "http://search.example.com" might contain, as a child of atom:feed. An identical link might appear as a child of any atom:entry whose content contains a discussion of that same search engine.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="self">
      <xs:annotation>
        <xs:documentation>The value "self" signifies that the IRI in the value of the href attribute identifies a resource equivalent to the containing element.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="enclosure">
      <xs:annotation>
        <xs:documentation>The value "enclosure" signifies that the IRI in the value of the href attribute identifies a related resource that is potentially large in size and might require special handling. For atom:link elements with rel="enclosure", the length attribute SHOULD be provided.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="via">
      <xs:annotation>
        <xs:documentation>The value "via" signifies that the IRI in the value of the href attribute identifies a resource that is the source of the information provided in the containing element.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
  </xs:restriction>
</xs:simpleType>