<xsd:element name="submitAction" minOccurs="0"> <xsd:complexType> <xsd:attribute name="adapter" type="xsf:xdTitle" use="required" /> </xsd:complexType> <xsd:keyref name="submitAdapter_name_keyref" refer="xsf:adapter_name_key"> <xsd:selector xpath="." /> <xsd:field xpath="@adapter" /> </xsd:keyref> </xsd:element>