The metadata elements, many of which map to Dublin core metadata, are available in topics and DITA maps. This design enables authors and information architects to use identical metadata markup in both topics and maps.
The metadata element is a wrapper element that contains many of the metadata elements. In topics, the metadata element is available in the prolog element. In maps, the metadata element is available in the topicmeta element.
In DITA maps, the metadata elements also are available directly in the topicmeta element. Collections of metadata can be shared between DITA maps and topics by using the conref or keyref mechanism.
In general, specifying metadata in a topicmeta element is equivalent to specifying it in the prolog element of a referenced topic. The value of specifying the metadata at the map level is that the topic then can be reused in other maps where different metadata might apply. Many items in the topicmeta element also cascade to nested topicref elements within the map.