<program name="relations" xmlns="http://www.crossref.org/relations.xsd">
  <related_item>{0,unbounded}</related_item>
</program>

<xsd:element name="program">
  <xsd:annotation>
    <xsd:documentation>Wrapper element for relationship metadata</xsd:documentation>
  </xsd:annotation>
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element ref="related_item" minOccurs="0" maxOccurs="unbounded"/>
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string" fixed="relations"/>
  </xsd:complexType>
</xsd:element>

<related_item xmlns="http://www.crossref.org/relations.xsd">
  <description language="">{0,1}</description>
  <inter_work_relation identifier-type="" namespace="" relationship-type="">{1,1}</inter_work_relation>
  <intra_work_relation identifier-type="" namespace="" relationship-type="">{1,1}</intra_work_relation>
</related_item>

<xsd:element name="related_item">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:annotation>
        <xsd:documentation>Description of the relationship to the target item or of the target item itself</xsd:documentation>
      </xsd:annotation>
      <xsd:element ref="description" minOccurs="0" maxOccurs="1"/>
      <xsd:choice>
        <xsd:element ref="inter_work_relation" minOccurs="1" maxOccurs="1"/>
        <xsd:element ref="intra_work_relation" minOccurs="1" maxOccurs="1"/>
      </xsd:choice>
    </xsd:sequence>
  </xsd:complexType>
</xsd:element>

<description language="" xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</description>

<xsd:element name="description">
  <xsd:annotation>
    <xsd:documentation>A narrative description of the relationship target item</xsd:documentation>
  </xsd:annotation>
  <xsd:complexType mixed="true">
    <xsd:choice minOccurs="0" maxOccurs="unbounded">
      <xsd:group ref="face_markup"/>
    </xsd:choice>
    <xsd:attributeGroup ref="language.atts"/>
  </xsd:complexType>
</xsd:element>

<b xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</b>

<xsd:element name="b" type="xrefFaces"/>

<i xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</i>

<xsd:element name="i" type="xrefFaces"/>

<em xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</em>

<xsd:element name="em" type="xrefFaces"/>

<strong xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</strong>

<xsd:element name="strong" type="xrefFaces"/>

<u xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</u>

<xsd:element name="u" type="xrefFaces"/>

<ovl xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</ovl>

<xsd:element name="ovl" type="xrefFaces"/>

<sup xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</sup>

<xsd:element name="sup" type="xrefFaces"/>

<sub xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</sub>

<xsd:element name="sub" type="xrefFaces"/>

<scp xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</scp>

<xsd:element name="scp" type="xrefFaces"/>

<tt xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</tt>

<xsd:element name="tt" type="xrefFaces"/>

<font xmlns="http://www.crossref.org/relations.xsd">
  <b>{1,1}</b>
  <i>{1,1}</i>
  <em>{1,1}</em>
  <strong>{1,1}</strong>
  <u>{1,1}</u>
  <ovl>{1,1}</ovl>
  <sup>{1,1}</sup>
  <sub>{1,1}</sub>
  <scp>{1,1}</scp>
  <tt>{1,1}</tt>
  <font>{1,1}</font>
</font>

<xsd:element name="font" type="xrefFaces"/>

<xsd:element name="inter_work_relation">
  <xsd:complexType mixed="true">
    <xsd:attribute name="relationship-type" use="required">
      <xsd:annotation>
        <xsd:documentation>Used to describe relations between items that are not the same work.</xsd:documentation>
      </xsd:annotation>
      <xsd:simpleType>
        <xsd:restriction base="xsd:string">
          <!--   Crossref  -->
          <xsd:enumeration value="isDerivedFrom"/>
          <!-- hasDerivation -->
          <xsd:enumeration value="hasDerivation"/>
          <!-- isDerivedFrom -->
          <xsd:enumeration value="isReviewOf"/>
          <!-- hasReview -->
          <xsd:enumeration value="hasReview"/>
          <!-- isReviewOf -->
          <xsd:enumeration value="isCommentOn"/>
          <!-- hasComment -->
          <xsd:enumeration value="hasComment"/>
          <!-- isCommentOn -->
          <xsd:enumeration value="isReplyTo"/>
          <!-- hasReply -->
          <xsd:enumeration value="hasReply"/>
          <!-- isReplyTo -->
          <xsd:enumeration value="basedOnData"/>
          <!-- isDataBasisFor -->
          <xsd:enumeration value="isDataBasisFor"/>
          <!-- basedOnData -->
          <xsd:enumeration value="hasRelatedMaterial"/>
          <!-- isRelatedMaterial -->
          <xsd:enumeration value="isRelatedMaterial"/>
          <!-- hasRelatedMaterial -->
          <!--   Common with DataCite  -->
          <xsd:enumeration value="isCompiledBy"/>
          <!-- compiles -->
          <xsd:enumeration value="compiles"/>
          <!-- isCompiledBy -->
          <xsd:enumeration value="isDocumentedBy"/>
          <!-- documents -->
          <xsd:enumeration value="documents"/>
          <!-- isDocumentedBy -->
          <xsd:enumeration value="isSupplementTo"/>
          <!-- isSupplememtedBy -->
          <xsd:enumeration value="isSupplementedBy"/>
          <!-- isSupplementTo -->
          <xsd:enumeration value="isContinuedBy"/>
          <!-- continues -->
          <xsd:enumeration value="continues"/>
          <!-- isContinuedBy -->
          <!--   From Dublin core -->
          <xsd:enumeration value="isPartOf"/>
          <!-- hasPart -->
          <xsd:enumeration value="hasPart"/>
          <!-- isPartOf -->
          <xsd:enumeration value="references"/>
          <!-- isReferencedBy -->
          <xsd:enumeration value="isReferencedBy"/>
          <!-- references -->
          <xsd:enumeration value="isBasedOn"/>
          <!-- isBasisFor -->
          <xsd:enumeration value="isBasisFor"/>
          <!-- isBasedOn -->
          <xsd:enumeration value="requires"/>
          <!-- isRequiredBy -->
          <xsd:enumeration value="isRequiredBy"/>
          <!-- requires -->
        </xsd:restriction>
      </xsd:simpleType>
    </xsd:attribute>
    <xsd:attributeGroup ref="relations_type.atts"/>
  </xsd:complexType>
</xsd:element>

<xsd:element name="intra_work_relation">
  <xsd:complexType mixed="true">
    <xsd:attribute name="relationship-type" use="required">
      <xsd:annotation>
        <xsd:documentation>Used to define relations between items that are essentially the same work but may differ in some way that impacts citation, for example a difference in format, language, or revision. Assigning different identifers to exactly the same item available in one place or as copies in multiple places can be problematic and should be avoided.</xsd:documentation>
      </xsd:annotation>
      <xsd:simpleType>
        <xsd:restriction base="xsd:string">
          <!--   Crossref  -->
          <xsd:enumeration value="isTranslationOf"/>
          <!-- hasTranslation -->
          <xsd:enumeration value="hasTranslation"/>
          <!-- isTranslationOf -->
          <xsd:enumeration value="isPreprintOf"/>
          <!-- hasPreprint -->
          <xsd:enumeration value="hasPreprint"/>
          <!-- isPreprintOf -->
          <xsd:enumeration value="isManuscriptOf"/>
          <!-- hasManuscript -->
          <xsd:enumeration value="hasManuscript"/>
          <!-- isManuscriptOf -->
          <xsd:enumeration value="isExpressionOf"/>
          <!-- hasExpression -->
          <xsd:enumeration value="hasExpression"/>
          <!-- isExpressionOf -->
          <xsd:enumeration value="isManifestationOf"/>
          <!-- hasManifestation -->
          <xsd:enumeration value="hasManifestation"/>
          <!-- isManifestationOf -->
          <xsd:enumeration value="isReplacedBy"/>
          <!-- replaces -->
          <xsd:enumeration value="replaces"/>
          <!-- isReplacedBy -->
          <xsd:enumeration value="isSameAs"/>
          <!-- isSameAs -->
          <!--   Common with DataCite  -->
          <xsd:enumeration value="isIdenticalTo"/>
          <!-- isIdenticalTo -->
          <xsd:enumeration value="isVariantFormOf"/>
          <!-- isOriginalFormOf -->
          <xsd:enumeration value="isOriginalFormOf"/>
          <!-- isVariantFormOf -->
          <!--   From Dublin core -->
          <xsd:enumeration value="isVersionOf"/>
          <!-- hasVersion -->
          <xsd:enumeration value="hasVersion"/>
          <!-- isVersionOf -->
          <xsd:enumeration value="isFormatOf"/>
          <!-- hasFormat -->
          <xsd:enumeration value="hasFormat"/>
          <!-- isFormatOf -->
        </xsd:restriction>
      </xsd:simpleType>
    </xsd:attribute>
    <xsd:attributeGroup ref="relations_type.atts"/>
  </xsd:complexType>
</xsd:element>

<xsd:complexType name="xrefFaces" mixed="true">
  <xsd:choice minOccurs="0" maxOccurs="unbounded">
    <xsd:group ref="face_markup"/>
  </xsd:choice>
</xsd:complexType>

<xsd:attributeGroup name="language.atts">
  <xsd:annotation>
    <xsd:documentation>Language attributes are based on ISO 639</xsd:documentation>
  </xsd:annotation>
  <xsd:attribute name="language" use="optional">
    <xsd:simpleType>
      <xsd:restriction base="xsd:NMTOKEN">
        <xsd:enumeration value="aa"/>
        <xsd:enumeration value="ab"/>
        <xsd:enumeration value="ae"/>
        <xsd:enumeration value="af"/>
        <xsd:enumeration value="ak"/>
        <xsd:enumeration value="am"/>
        <xsd:enumeration value="an"/>
        <xsd:enumeration value="ar"/>
        <xsd:enumeration value="as"/>
        <xsd:enumeration value="av"/>
        <xsd:enumeration value="ay"/>
        <xsd:enumeration value="az"/>
        <xsd:enumeration value="ba"/>
        <xsd:enumeration value="be"/>
        <xsd:enumeration value="bg"/>
        <xsd:enumeration value="bh"/>
        <xsd:enumeration value="bi"/>
        <xsd:enumeration value="bm"/>
        <xsd:enumeration value="bn"/>
        <xsd:enumeration value="bo"/>
        <xsd:enumeration value="br"/>
        <xsd:enumeration value="bs"/>
        <xsd:enumeration value="ca"/>
        <xsd:enumeration value="ce"/>
        <xsd:enumeration value="ch"/>
        <xsd:enumeration value="co"/>
        <xsd:enumeration value="cr"/>
        <xsd:enumeration value="cs"/>
        <xsd:enumeration value="cu"/>
        <xsd:enumeration value="cv"/>
        <xsd:enumeration value="cy"/>
        <xsd:enumeration value="da"/>
        <xsd:enumeration value="de"/>
        <xsd:enumeration value="dv"/>
        <xsd:enumeration value="dz"/>
        <xsd:enumeration value="ee"/>
        <xsd:enumeration value="el"/>
        <xsd:enumeration value="en"/>
        <xsd:enumeration value="eo"/>
        <xsd:enumeration value="es"/>
        <xsd:enumeration value="et"/>
        <xsd:enumeration value="eu"/>
        <xsd:enumeration value="fa"/>
        <xsd:enumeration value="ff"/>
        <xsd:enumeration value="fi"/>
        <xsd:enumeration value="fj"/>
        <xsd:enumeration value="fo"/>
        <xsd:enumeration value="fr"/>
        <xsd:enumeration value="fy"/>
        <xsd:enumeration value="ga"/>
        <xsd:enumeration value="gd"/>
        <xsd:enumeration value="gl"/>
        <xsd:enumeration value="gn"/>
        <xsd:enumeration value="gu"/>
        <xsd:enumeration value="gv"/>
        <xsd:enumeration value="ha"/>
        <xsd:enumeration value="he"/>
        <xsd:enumeration value="hi"/>
        <xsd:enumeration value="ho"/>
        <xsd:enumeration value="hr"/>
        <xsd:enumeration value="ht"/>
        <xsd:enumeration value="hu"/>
        <xsd:enumeration value="hy"/>
        <xsd:enumeration value="hz"/>
        <xsd:enumeration value="ia"/>
        <xsd:enumeration value="id"/>
        <xsd:enumeration value="ie"/>
        <xsd:enumeration value="ig"/>
        <xsd:enumeration value="ii"/>
        <xsd:enumeration value="ik"/>
        <xsd:enumeration value="io"/>
        <xsd:enumeration value="is"/>
        <xsd:enumeration value="it"/>
        <xsd:enumeration value="iu"/>
        <xsd:enumeration value="ja"/>
        <xsd:enumeration value="jw"/>
        <xsd:enumeration value="ka"/>
        <xsd:enumeration value="kg"/>
        <xsd:enumeration value="ki"/>
        <xsd:enumeration value="kj"/>
        <xsd:enumeration value="kk"/>
        <xsd:enumeration value="kl"/>
        <xsd:enumeration value="km"/>
        <xsd:enumeration value="kn"/>
        <xsd:enumeration value="ko"/>
        <xsd:enumeration value="kr"/>
        <xsd:enumeration value="ks"/>
        <xsd:enumeration value="ku"/>
        <xsd:enumeration value="kv"/>
        <xsd:enumeration value="kw"/>
        <xsd:enumeration value="ky"/>
        <xsd:enumeration value="la"/>
        <xsd:enumeration value="lb"/>
        <xsd:enumeration value="lg"/>
        <xsd:enumeration value="li"/>
        <xsd:enumeration value="ln"/>
        <xsd:enumeration value="lo"/>
        <xsd:enumeration value="lt"/>
        <xsd:enumeration value="lu"/>
        <xsd:enumeration value="lv"/>
        <xsd:enumeration value="mg"/>
        <xsd:enumeration value="mu"/>
        <xsd:enumeration value="mi"/>
        <xsd:enumeration value="mk"/>
        <xsd:enumeration value="ml"/>
        <xsd:enumeration value="mn"/>
        <xsd:enumeration value="mr"/>
        <xsd:enumeration value="ms"/>
        <xsd:enumeration value="mt"/>
        <xsd:enumeration value="my"/>
        <xsd:enumeration value="na"/>
        <xsd:enumeration value="nb"/>
        <xsd:enumeration value="nd"/>
        <xsd:enumeration value="ne"/>
        <xsd:enumeration value="ng"/>
        <xsd:enumeration value="nl"/>
        <xsd:enumeration value="nn"/>
        <xsd:enumeration value="no"/>
        <xsd:enumeration value="nr"/>
        <xsd:enumeration value="nv"/>
        <xsd:enumeration value="ny"/>
        <xsd:enumeration value="oc"/>
        <xsd:enumeration value="oj"/>
        <xsd:enumeration value="om"/>
        <xsd:enumeration value="or"/>
        <xsd:enumeration value="os"/>
        <xsd:enumeration value="pa"/>
        <xsd:enumeration value="pi"/>
        <xsd:enumeration value="pl"/>
        <xsd:enumeration value="ps"/>
        <xsd:enumeration value="pt"/>
        <xsd:enumeration value="qu"/>
        <xsd:enumeration value="rm"/>
        <xsd:enumeration value="rn"/>
        <xsd:enumeration value="ro"/>
        <xsd:enumeration value="ru"/>
        <xsd:enumeration value="rw"/>
        <xsd:enumeration value="sa"/>
        <xsd:enumeration value="sc"/>
        <xsd:enumeration value="sd"/>
        <xsd:enumeration value="se"/>
        <xsd:enumeration value="sg"/>
        <xsd:enumeration value="si"/>
        <xsd:enumeration value="sk"/>
        <xsd:enumeration value="sl"/>
        <xsd:enumeration value="sm"/>
        <xsd:enumeration value="sn"/>
        <xsd:enumeration value="so"/>
        <xsd:enumeration value="sq"/>
        <xsd:enumeration value="sr"/>
        <xsd:enumeration value="ss"/>
        <xsd:enumeration value="st"/>
        <xsd:enumeration value="su"/>
        <xsd:enumeration value="sv"/>
        <xsd:enumeration value="sw"/>
        <xsd:enumeration value="ta"/>
        <xsd:enumeration value="te"/>
        <xsd:enumeration value="tg"/>
        <xsd:enumeration value="th"/>
        <xsd:enumeration value="ti"/>
        <xsd:enumeration value="tk"/>
        <xsd:enumeration value="tl"/>
        <xsd:enumeration value="tn"/>
        <xsd:enumeration value="to"/>
        <xsd:enumeration value="tr"/>
        <xsd:enumeration value="ts"/>
        <xsd:enumeration value="tt"/>
        <xsd:enumeration value="tw"/>
        <xsd:enumeration value="ty"/>
        <xsd:enumeration value="ug"/>
        <xsd:enumeration value="uk"/>
        <xsd:enumeration value="ur"/>
        <xsd:enumeration value="uz"/>
        <xsd:enumeration value="ve"/>
        <xsd:enumeration value="vi"/>
        <xsd:enumeration value="vo"/>
        <xsd:enumeration value="wa"/>
        <xsd:enumeration value="wo"/>
        <xsd:enumeration value="xh"/>
        <xsd:enumeration value="yi"/>
        <xsd:enumeration value="yo"/>
        <xsd:enumeration value="za"/>
        <xsd:enumeration value="zh"/>
      </xsd:restriction>
    </xsd:simpleType>
  </xsd:attribute>
</xsd:attributeGroup>

<xsd:attributeGroup name="relations_type.atts">
  <xsd:attribute name="identifier-type" use="required">
    <xsd:simpleType>
      <xsd:restriction base="xsd:string">
        <xsd:enumeration value="doi"/>
        <xsd:enumeration value="issn"/>
        <xsd:enumeration value="isbn"/>
        <xsd:enumeration value="uri"/>
        <xsd:enumeration value="pmid"/>
        <xsd:enumeration value="pmcid"/>
        <xsd:enumeration value="purl"/>
        <xsd:enumeration value="arxiv"/>
        <xsd:enumeration value="ark"/>
        <xsd:enumeration value="handle"/>
        <xsd:enumeration value="uuid"/>
        <xsd:enumeration value="ecli"/>
        <xsd:enumeration value="accession"/>
        <xsd:enumeration value="other"/>
      </xsd:restriction>
    </xsd:simpleType>
  </xsd:attribute>
  <xsd:attribute name="namespace">
    <xsd:annotation>
      <xsd:documentation>An identifier systems may require a namespace that is needed in addition to the identifer value to provide uniqueness.</xsd:documentation>
    </xsd:annotation>
    <xsd:simpleType>
      <xsd:restriction base="xsd:string">
        <xsd:maxLength value="1024"/>
        <xsd:minLength value="4"/>
      </xsd:restriction>
    </xsd:simpleType>
  </xsd:attribute>
</xsd:attributeGroup>