<xs:element name="TopicSetRef">
    <xs:annotation>
        <xs:documentation> 
================================= TopicSetRef ==================================
A pointer to a TopicSet that is to be merged with the current one. The TopicSet
attribute is a pointer to the relevant TopicSet. Its value can be an http URL,
or a NewsML URN as described in the comment to PublicIdentifier, or a fragment
identifier consisting of a # character followed by the Duid of a TopicSet in the
current document. The presence of a TopicSetRef child in a TopicSet has the
effect that all the Topics in the referenced TopicSet are included by reference
within the current TopicSet. When this merging results in there exising two
FormalName grandchildren of the same TopicSet that have the same content and
the same Scheme attribute value, then the Topics whose children are in fact the
same topic, and are deemed to be merged. The merging of Topics need not be
performed physically by the system, but the meaning of the data is
exactly the same as if the merging were actually performed. Merging two
Topcis consists of creating a single Topic that contains all the children of
both, and eliminating duplicates.
================================================================================

			</xs:documentation>
    </xs:annotation>
    <xs:complexType>
        <xs:sequence>
            <xs:element ref="Comment" minOccurs="0" maxOccurs="unbounded" />
        </xs:sequence>
        <xs:attributeGroup ref="localid" />
        <xs:attribute name="TopicSet" type="xs:string" />
    </xs:complexType>
</xs:element>