<xs:attribute name="PersonalIdentifierScheme">
  <xs:annotation>
    <xs:appinfo>
      <identifier>http://purl.org/spar/datacite/PersonalIdentifierScheme</identifier>
      <subclassOf>http://purl.org/spar/datacite/AgentIdentifierScheme</subclassOf>
    </xs:appinfo>
  </xs:annotation>
  <xs:simpleType>
    <xs:restriction base="xs:anyURI">
      <xs:enumeration value="http://purl.org/spar/datacite/openid">
        <xs:annotation>
          <xs:documentation xml:lang="en">OpenID is an open standard that describes how users can be authenticated in a decentralized manner, eliminating the need for centralized registration services.</xs:documentation>
          <xs:appinfo>
            <identifier>http://purl.org/spar/datacite/openid</identifier>
            <label xml:lang="en">OpenID</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="http://purl.org/spar/datacite/orcid">
        <xs:annotation>
          <xs:documentation xml:lang="en">Open Researcher and Contributor Identifier.</xs:documentation>
          <xs:appinfo>
            <identifier>http://purl.org/spar/datacite/orcid</identifier>
            <label xml:lang="en">ORCID</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="http://purl.org/spar/datacite/researcherid">
        <xs:annotation>
          <xs:documentation xml:lang="en">ResearcherID is an identifying system for scientific authors created and owned by Thomson Reuters.</xs:documentation>
          <xs:appinfo>
            <identifier>http://purl.org/spar/datacite/researcherid</identifier>
            <label xml:lang="en">ResearcherID</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="http://w3id.org/meta-share/meta-share/elg">
        <xs:annotation>
          <xs:documentation xml:lang="en">European Language Grid</xs:documentation>
          <xs:appinfo>
            <identifier>http://w3id.org/meta-share/meta-share/elg</identifier>
            <label xml:lang="en">ELG</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="http://w3id.org/meta-share/meta-share/other">
        <xs:annotation>
          <xs:appinfo>
            <identifier>http://w3id.org/meta-share/meta-share/other</identifier>
            <label xml:lang="en">other</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="http://w3id.org/meta-share/meta-share/scopusId">
        <xs:annotation>
          <xs:documentation xml:lang="en">Value for personIdentifierSchemeName, referring to the Scopus identifier for authors (https://www.scopus.com)</xs:documentation>
          <xs:appinfo>
            <identifier>http://w3id.org/meta-share/meta-share/scopusId</identifier>
            <label xml:lang="en">Scopus ID</label>
          </xs:appinfo>
        </xs:annotation>
      </xs:enumeration>
    </xs:restriction>
  </xs:simpleType>
</xs:attribute>