<!-- ............................................................. -->
<!-- XML Topic Map DTD  .......................................... -->

<!-- XML Topic Map (XTM) DTD, Version 2.0

     This is XTM 2.0, an XML interchange syntax for ISO 13250 Topic
     Maps, defined by ISO 13250-3.

     Use this URI to identify the XTM namespace:

         "http://www.topicmaps.org/xtm/"

     The formal public identifier for this DTD is:
         
         "ISO/IEC 13250-3:2005//DTD XML Topic Maps (XTM) 2.0//EN"

     See http://www.isotopicmaps.org/sam/sam-xtm/

-->

<!-- topicMap .................................................... -->

<!ELEMENT topicMap
   ( itemIdentity*, mergeMap*, ( topic | association )* )
>
<!ATTLIST topicMap
   version         CDATA     #FIXED '2.0'
   xmlns           CDATA     #FIXED 'http://www.topicmaps.org/xtm/'
   reifier         CDATA     #IMPLIED
>

<!-- topic ....................................................... -->

<!ELEMENT topic
   ( ( itemIdentity | subjectLocator | subjectIdentifier )*,
     instanceOf?, ( name | occurrence )* )
>
<!ATTLIST topic
   id              ID        #REQUIRED
>

<!-- itemIdentity ................................................ -->

<!ELEMENT itemIdentity
   EMPTY
>
<!ATTLIST itemIdentity
   href            CDATA     #REQUIRED
>

<!-- subjectLocator............................................... -->

<!ELEMENT subjectLocator
   EMPTY
>
<!ATTLIST subjectLocator
   href            CDATA     #REQUIRED
>

<!-- subjectIdentifier............................................ -->

<!ELEMENT subjectIdentifier
   EMPTY
>
<!ATTLIST subjectIdentifier
   href            CDATA     #REQUIRED
>

<!-- name ........................................................ -->

<!ELEMENT name  
   ( itemIdentity*, type?, scope?, value, variant* ) 
>
<!ATTLIST name
   reifier         CDATA     #IMPLIED
>

<!-- value ....................................................... -->

<!ELEMENT value  ( #PCDATA ) >

<!-- variant ..................................................... -->

<!ELEMENT variant  
   ( itemIdentity*, scope, ( resourceRef | resourceData ) ) 
>
<!ATTLIST variant
   reifier         CDATA     #IMPLIED
>

<!-- scope ....................................................... -->

<!ELEMENT scope  
   ( topicRef )+ 
>

<!-- instanceOf .................................................. -->

<!ELEMENT instanceOf  
   ( topicRef )+
>

<!-- type .................................................. -->

<!ELEMENT type  
   ( topicRef )
>

<!-- occurrence .................................................. -->

<!ELEMENT occurrence
   ( itemIdentity*, type, scope?, ( resourceRef | resourceData ) )
>
<!ATTLIST occurrence
   reifier         CDATA     #IMPLIED
>

<!-- resourceData ................................................ -->

<!ELEMENT resourceData  
   ANY 
>
<!ATTLIST resourceData
   datatype        CDATA     #IMPLIED
>

<!-- resourceRef ................................................. -->

<!ELEMENT resourceRef  
   EMPTY 
>
<!ATTLIST resourceRef
   href            CDATA     #REQUIRED
>

<!-- association ................................................. -->

<!ELEMENT association
   ( itemIdentity*, type, scope?, role+ )
>
<!ATTLIST association
   reifier         CDATA     #IMPLIED
>

<!-- role ........................................................ -->

<!ELEMENT role
   ( itemIdentity*, type, topicRef )
>
<!ATTLIST role
   reifier         CDATA     #IMPLIED
>

<!-- topicRef .................................................... -->

<!ELEMENT topicRef  
   EMPTY 
>
<!ATTLIST topicRef
   href            CDATA     #REQUIRED
>

<!-- mergeMap .................................................... -->

<!ELEMENT mergeMap  
   EMPTY
>
<!ATTLIST mergeMap
   href            CDATA     #REQUIRED
>

<!-- end of XML Topic Map (XTM) 2.0 DTD .......................... -->