The current protocol schema advertises mapped concepts as part of the capabilities response. Here's the related part in the XML Schema:

<verbatim>
<xsd:element name="concepts">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element name="conceptNameServers">
        <xsd:complexType>
          <xsd:sequence>
            <xsd:element name="server" type="externalResourceType" maxOccurs="unbounded">
            </xsd:element>
          </xsd:sequence>
        </xsd:complexType>
      </xsd:element>
      <xsd:element name="schema" maxOccurs="unbounded">
        <xsd:complexType>
          <xsd:sequence>
            <xsd:element name="mappedConcept" maxOccurs="unbounded">
              <xsd:complexType>
                <xsd:complexContent>
                  <xsd:extension base="qualifiedConceptReferenceType">
                    <xsd:attribute name="searchable" type="xsd:boolean" use="optional" default="true"/>
                    <xsd:attribute name="mandatory" type="xsd:boolean" use="optional" default="false"/>
                  </xsd:extension>
                </xsd:complexContent>
              </xsd:complexType>
            </xsd:element>
          </xsd:sequence>
          <xsd:attribute name="namespace" type="xsd:anyURI" use="required"/>
          <xsd:attribute name="location" type="xsd:anyURI" use="required"/>
        </xsd:complexType>
      </xsd:element>
    </xsd:sequence>
  </xsd:complexType>
</xsd:element>
</verbatim>

The suggested changes to support semantic mapping are:

   * Concepts are now classes, properties or relationships.
   * Properties and relationships (associations) are defined inside classes.
   * All types of concepts are defined under a single <mapping> element.
   * The <schema> element (unbounded) was replaced by a <source> element, specifying only namespace and location for each ontology referenced by concepts in the <mapping>.
   * Any mapped class, property or relationship must be defined in one of the source ontologies.

<verbatim>
<xsd:element name="concepts">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element name="conceptNameServers">
        <xsd:complexType>
          <xsd:sequence>
            <xsd:element name="server" type="externalResourceType" maxOccurs="unbounded">
            </xsd:element>
          </xsd:sequence>
        </xsd:complexType>
      </xsd:element>
      <xsd:element name="source" maxOccurs="unbounded">
        <xsd:complexType>
          <xsd:attribute name="namespace" type="xsd:anyURI" use="required"/>
          <xsd:attribute name="location" type="xsd:anyURI" use="required"/>
        </xsd:complexType>
      </xsd:element>
      <xsd:element name="mapping">
        <xsd:complexType>
          <xsd:sequence>
            <xsd:element name="class" maxOccurs="unbounded">
              <xsd:complexType>
                <xsd:complexContent>
                  <xsd:extension base="qualifiedConceptReferenceType">
                    <xsd:sequence>
                      <xsd:element name="property" maxOccurs="unbounded">
                        <xsd:complexType>
                          <xsd:complexContent>
                            <xsd:extension base="qualifiedConceptReferenceType">
                              <xsd:attribute name="searchable" type="xsd:boolean" use="optional" default="true"/>
                              <xsd:attribute name="mandatory" type="xsd:boolean" use="optional" default="false"/>
                            </xsd:extension>
                          </xsd:complexContent>
                        </xsd:complexType>
                      </xsd:element>
                      <xsd:element name="relationship" maxOccurs="unbounded">
                        <xsd:complexType>
                          <xsd:complexContent>
                            <xsd:extension base="qualifiedConceptReferenceType">
                              <xsd:attribute name="myRole" type="xsd:string" use="required"/>
                              <xsd:attribute name="withClass" type="xsd:qualifiedConceptIdType" use="required"/>
                              <xsd:attribute name="othersRole" type="xsd:string" use="required"/>
                            </xsd:extension>
                          </xsd:complexContent>
                        </xsd:complexType>
                      </xsd:element>
                    </xsd:sequence>
                  </xsd:extension>
                </xsd:complexContent>
              </xsd:complexType>
            </xsd:element>
          </xsd:sequence>
        </xsd:complexType>
      </xsd:element>
    </xsd:sequence>
  </xsd:complexType>
</xsd:element>
</verbatim>