<schema targetNamespace="http://www.openarchives.org/OAI/2.0/"
        xmlns="http://www.w3.org/2001/XMLSchema"
        xmlns:oai="http://www.openarchives.org/OAI/2.0/"
        elementFormDefault="qualified"
        attributeFormDefault="unqualified">

  <annotation>
    <documentation>
    XML Schema which can be used to validate replies to all OAI-PMH 
    v2.0 requests. Herbert Van de Sompel, 2002-05-13.
    Validated with XML Spy v.4.3 on 2002-05-13.
    Validated with XSV 1.203.2.45/1.106.2.22 on 2002-05-13.
    Added definition of protocolVersionType instead of using anonymous 
    type. No change of function. Simeon Warner, 2004-03-29.
    Tightened definition of UTCdatetimeType to enforce the restriction 
    to UTC Z notation. Simeon Warner, 2004-09-14.
    Corrected pattern matches for setSpecType and metedataPrefixType
    to agree with protocol specification. Simeon Warner, 2004-10-12.
    $Date: 2004/10/12 15:20:29 $
    </documentation>
  </annotation>

  <element name="OAI-PMH" type="oai:OAI-PMHtype"/>

  <complexType name="OAI-PMHtype">
    <sequence>
      <element name="responseDate" type="dateTime"/>
      <element name="request" type="oai:requestType"/>
      <choice>
        <element name="error" type="oai:OAI-PMHerrorType" maxOccurs="unbounded"/>
        <element name="Identify" type="oai:IdentifyType"/>
        <element name="ListMetadataFormats" type="oai:ListMetadataFormatsType"/>
        <element name="ListSets" type="oai:ListSetsType"/>
        <element name="GetRecord" type="oai:GetRecordType"/>
        <element name="ListIdentifiers" type="oai:ListIdentifiersType"/>
        <element name="ListRecords" type="oai:ListRecordsType"/>
      </choice>
    </sequence>
  </complexType>

  <complexType name="requestType">
    <annotation>
      <documentation>Define requestType, indicating the protocol request that 
      led to the response. Element content is BASE-URL, attributes are arguments 
      of protocol request, attribute-values are values of arguments of protocol 
      request</documentation>
    </annotation>
    <simpleContent>
      <extension base="anyURI">
        <attribute name="verb" type="oai:verbType" use="optional"/>
        <attribute name="identifier" type="oai:identifierType" use="optional"/>
        <attribute name="metadataPrefix" type="oai:metadataPrefixType" use="optional"/>
        <attribute name="from" type="oai:UTCdatetimeType" use="optional"/>
        <attribute name="until" type="oai:UTCdatetimeType" use="optional"/>
        <attribute name="set" type="oai:setSpecType" use="optional"/>
        <attribute name="resumptionToken" type="string" use="optional"/>
      </extension>
    </simpleContent>
  </complexType>

  <simpleType name="verbType">
    <restriction base="string">
      <enumeration value="Identify"/>
      <enumeration value="ListMetadataFormats"/>
      <enumeration value="ListSets"/>
      <enumeration value="GetRecord"/>
      <enumeration value="ListIdentifiers"/>
      <enumeration value="ListRecords"/>
    </restriction>
  </simpleType>

  <!-- define OAI-PMH error conditions -->
  <!-- =============================== -->

  <complexType name="OAI-PMHerrorType">
    <simpleContent>
      <extension base="string">
        <attribute name="code" type="oai:OAI-PMHerrorcodeType" use="required"/>
      </extension>
    </simpleContent>
  </complexType>

  <simpleType name="OAI-PMHerrorcodeType">
    <restriction base="string">
      <enumeration value="cannotDisseminateFormat"/>
      <enumeration value="idDoesNotExist"/>
      <enumeration value="badArgument"/>
      <enumeration value="badVerb"/>
      <enumeration value="noMetadataFormats"/>
      <enumeration value="noRecordsMatch"/>
      <enumeration value="badResumptionToken"/>
      <enumeration value="noSetHierarchy"/>
    </restriction>
  </simpleType>

  <!-- define OAI-PMH verb containers -->
  <!-- ============================== -->

  <complexType name="IdentifyType">
    <sequence>
      <element name="repositoryName" type="string"/>
      <element name="baseURL" type="anyURI"/>
      <element name="protocolVersion" type="oai:protocolVersionType"/>
      <element name="adminEmail" type="oai:emailType" maxOccurs="unbounded"/>
      <element name="earliestDatestamp" type="oai:UTCdatetimeType"/>
      <element name="deletedRecord" type="oai:deletedRecordType"/>
      <element name="granularity" type="oai:granularityType"/>
      <element name="compression" type="string" minOccurs="0" maxOccurs="unbounded"/>
      <element name="description" type="oai:descriptionType" 
               minOccurs="0" maxOccurs="unbounded"/>
    </sequence>
  </complexType>

  <complexType name="ListMetadataFormatsType">
    <sequence>
      <element name="metadataFormat" type="oai:metadataFormatType" maxOccurs="unbounded"/>
    </sequence>
  </complexType>

  <complexType name="ListSetsType">
    <sequence>
      <element name="set" type="oai:setType" maxOccurs="unbounded"/>
      <element name="resumptionToken" type="oai:resumptionTokenType" minOccurs="0"/>
    </sequence>
  </complexType>

  <complexType name="GetRecordType">
    <sequence>
      <element name="record" type="oai:recordType"/>
    </sequence>
  </complexType>

  <complexType name="ListRecordsType">
    <sequence>
      <element name="record" type="oai:recordType" maxOccurs="unbounded"/>
      <element name="resumptionToken" type="oai:resumptionTokenType" minOccurs="0"/>
    </sequence>
  </complexType>

  <complexType name="ListIdentifiersType">
    <sequence>
      <element name="header" type="oai:headerType" maxOccurs="unbounded"/>
      <element name="resumptionToken" type="oai:resumptionTokenType" minOccurs="0"/>
    </sequence>
  </complexType>

  <!-- define basic types used in replies to 
       GetRecord, ListRecords, ListIdentifiers -->
  <!-- ======================================= -->

  <complexType name="recordType">
    <annotation>
      <documentation>A record has a header, a metadata part, and
        an optional about container</documentation>
    </annotation>
    <sequence>
      <element name="header" type="oai:headerType"/>
      <element name="metadata" type="oai:metadataType" minOccurs="0"/>
      <element name="about" type="oai:aboutType" minOccurs="0" maxOccurs="unbounded"/>
    </sequence>
  </complexType>

  <complexType name="headerType">
    <annotation>
      <documentation>A header has a unique identifier, a datestamp,
        and setSpec(s) in case the item from which
        the record is disseminated belongs to set(s).
        the header can carry a deleted status indicating
        that the record is deleted.</documentation>
    </annotation>
    <sequence>
      <element name="identifier" type="oai:identifierType"/>
      <element name="datestamp" type="oai:UTCdatetimeType"/>
      <element name="setSpec" type="oai:setSpecType" minOccurs="0" maxOccurs="unbounded"/>
    </sequence>
    <attribute name="status" type="oai:statusType" use="optional"/>
  </complexType>

  <simpleType name="identifierType">
    <restriction base="anyURI"/>
  </simpleType>

  <simpleType name="statusType">
    <restriction base="string">
      <enumeration value="deleted"/>
    </restriction>
  </simpleType>

  <complexType name="metadataType">
    <annotation>
      <documentation>Metadata must be expressed in XML that complies
       with another XML Schema (namespace=#other). Metadata must be 
       explicitly qualified in the response.</documentation>
    </annotation>
    <sequence>
      <any namespace="##other" processContents="strict"/>
    </sequence>
  </complexType>

  <complexType name="aboutType">
    <annotation>
      <documentation>Data "about" the record must be expressed in XML
      that is compliant with an XML Schema defined by a community.</documentation>
    </annotation>
    <sequence>
      <any namespace="##other" processContents="strict"/>
    </sequence>
  </complexType>

  <complexType name="resumptionTokenType">
    <annotation>
      <documentation>A resumptionToken may have 3 optional attributes
       and can be used in ListSets, ListIdentifiers, ListRecords
       responses.</documentation>
    </annotation>
    <simpleContent>
      <extension base="string">
        <attribute name="expirationDate" type="dateTime" use="optional"/>
        <attribute name="completeListSize" type="positiveInteger" use="optional"/>
        <attribute name="cursor" type="nonNegativeInteger" use="optional"/>
      </extension>
    </simpleContent>
  </complexType>

  <complexType name="descriptionType">
    <annotation>
      <documentation>The descriptionType is used for the description
      element in Identify and for setDescription element in ListSets.
      Content must be compliant with an XML Schema defined by a 
      community.</documentation>
    </annotation>
    <sequence>
      <any namespace="##other" processContents="strict"/>
    </sequence>
  </complexType>

  <simpleType name="UTCdatetimeType">
    <annotation>
      <documentation>Datestamps are to either day (type date)
      or to seconds granularity (type oai:UTCdateTimeZType)</documentation>
    </annotation>
    <union memberTypes="date oai:UTCdateTimeZType"/>
  </simpleType>

  <simpleType name="UTCdateTimeZType">
    <restriction base="dateTime">
      <pattern value=".*Z"/>
    </restriction>
  </simpleType>

  <!-- define types used for Identify verb only -->
  <!-- ======================================== -->

  <simpleType name="protocolVersionType">
    <restriction base="string">
      <enumeration value="2.0"/>
    </restriction>
  </simpleType>

  <simpleType name="emailType">
    <restriction base="string">
      <pattern value="\S+@(\S+\.)+\S+"/>
    </restriction>
  </simpleType>

  <simpleType name="deletedRecordType">
    <restriction base="string">
      <enumeration value="no"/>
      <enumeration value="persistent"/>
      <enumeration value="transient"/>
    </restriction>
  </simpleType>

  <simpleType name="granularityType">
    <restriction base="string">
      <enumeration value="YYYY-MM-DD"/>
      <enumeration value="YYYY-MM-DDThh:mm:ssZ"/>
    </restriction>
  </simpleType>

  <!-- define types used for ListMetadataFormats verb only -->
  <!-- =================================================== -->

  <complexType name="metadataFormatType">
    <sequence>
      <element name="metadataPrefix" type="oai:metadataPrefixType"/>
      <element name="schema" type="anyURI"/>
      <element name="metadataNamespace" type="anyURI"/>
    </sequence>
  </complexType>

  <simpleType name="metadataPrefixType">
    <restriction base="string">
      <pattern value="[A-Za-z0-9\-_\.!~\*'\(\)]+"/>
    </restriction>
  </simpleType>

  <!-- define types used for ListSets verb -->
  <!-- =================================== -->

  <complexType name="setType">
    <sequence>
      <element name="setSpec" type="oai:setSpecType"/>
      <element name="setName" type="string"/>
      <element name="setDescription" type="oai:descriptionType" 
               minOccurs="0" maxOccurs="unbounded"/>
    </sequence>
  </complexType>

  <simpleType name="setSpecType">
    <restriction base="string">
      <pattern value="([A-Za-z0-9\-_\.!~\*'\(\)])+(:[A-Za-z0-9\-_\.!~\*'\(\)]+)*"/>
    </restriction>
  </simpleType>

</schema>
