<xs:element name="concept">
  <xs:annotation>
    <xs:documentation>A concept object: contains the first concept (name, reference, id), the second concept(name, reference, id) and the relation between the 2 concepts</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="name"/>
      <xs:element ref="status"/>
      <xs:element ref="reference"/>
      <xs:element ref="relationSet" minOccurs="0"/>
      <xs:element ref="reference_2" minOccurs="0"/>
    </xs:sequence>
    <xs:attribute name="dataSchemaConcept" type="xs:string" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="conceptSet">
  <xs:annotation>
    <xs:documentation>The set of concepts (pair of concepts)</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="concept"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="error">
  <xs:complexType>
    <xs:attribute name="code" type="xs:int" use="required"/>
    <xs:attribute name="message" type="xs:string" use="required"/>
    <xs:attribute name="detail" type="xs:string" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="name">
  <xs:annotation>
    <xs:documentation>2 concepts and their relation ; value: the name of the searched concept.</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="id" type="xs:string" use="required">
          <xs:annotation>
            <xs:documentation>ID of the searched/first concept</xs:documentation>
          </xs:annotation>
        </xs:attribute>
        <xs:attribute name="relationtype" type="xs:string" use="required">
          <xs:annotation>
            <xs:documentation>relation existing between the 2 concepts</xs:documentation>
          </xs:annotation>
        </xs:attribute>
        <xs:attribute name="id2" type="xs:string" use="required">
          <xs:annotation>
            <xs:documentation>ID of the second concept</xs:documentation>
          </xs:annotation>
        </xs:attribute>
        <xs:attribute name="name" type="xs:string" use="required">
          <xs:annotation>
            <xs:documentation>name of the second concept</xs:documentation>
          </xs:annotation>
        </xs:attribute>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

<xs:element name="reference">
  <xs:annotation>
    <xs:documentation>The reference (name+ID) of the first concept</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="id" use="required"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

<xs:element name="reference_2">
  <xs:annotation>
    <xs:documentation>The reference (name+ID) of the second concept</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="id" type="xs:string" use="required"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

<xs:element name="relation">
  <xs:annotation>
    <xs:documentation>The relation type existing between the two concepts</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="concept" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="name" type="xs:string" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="relationSet">
  <xs:annotation>
    <xs:documentation>A set of relation existing for the searched concept</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="relation"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="response">
  <xs:annotation>
    <xs:documentation>Defines the document as a toqe response instance</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="conceptSet" minOccurs="0"/>
      <xs:element ref="error" minOccurs="0"/>
    </xs:sequence>
    <xs:attribute name="success" type="xs:boolean" use="required"/>
  </xs:complexType>
</xs:element>

<xs:element name="status">
  <xs:annotation>
    <xs:documentation>The status (accepted, synonym) of the current concept</xs:documentation>
  </xs:annotation>
</xs:element>