TMTab is no longer under active development. The last version of Protégé that it is known to work with is Protégé 2.1.2.
TMTab is a plugin for Protégé that allows you to build an ontology which may be exported as a topic map in XTM syntax.
The plugin comes with a base ontology for topic map constructs - such as topics, associations, occurrences and so on - and allows you to create your own derived classes which further constrain the base topic map ontology. Using this tab you can, for example mandate that an association of type "born-in" must be an association between exactly one instance of the "person" topic and one instance of the "place" topic. Better yet, because these constraints are encoded using Protégé's slot constraints, the editing application will automatically present the user with only the topic instances which are valid in a given context.
TMTab's export process is also smart enough to enable topic names, occurrences and simple binary associations all to be specified using slots on the Protégé instance that represents the topic. This enables the topic map author to enter all data regarding a topic on a single form.