What Is XTM?

• XML Topic Maps. A generic language for capturing and interchanging knowledge.
• A language for defining taxonomies and ontologies and applying them to resources on the Web.
• An open specification developed by TopicMaps.org and now being incorporated into the ISO/IEC Topic Map standard (ISO/IEC 13250).

Benefits:

Information and Knowledge Management

• Provides a generic, implementation-independent format for taxonomies and ontologies.
• Separates capture and maintenance of business models from applications and tools that reflect or implement those business models.
• Allows knowledge to be aggregated, interchanged, and re-used in many contexts.
• Enables use of inference engines and other AI technologies on captured knowledge.
• Enables layering of navigation and indexing information on top of existing information bases, such as business documents, databases, and, Web sites.
• Enables application-to-application interoperability for knowledge management.

Storage/Retrieval of Data

• Provides a generic definition of the metadata that storage and retrieval systems must support for a given set of information.
• Can be used to help users construct appropriate queries.
• Enables many navigation and retrieval views of databases.

How It Works:

Topic Maps provide for the specification of a standard, interchangeable hypertext navigation layer above diverse electronic information sources. Topic Maps enable the creation of virtual information maps for the Web, Intranets, or even print materials. Topic Maps were originally developed as a way to generalize and standardize the way that back-of-the-book indexes and thesauruses could be represented. This led to a simple but powerful set of structures capable of representing knowledge generally. From this beginning the focus of topic maps and their use shifted to the task of capturing and interchanging knowledge generally.

Topic Maps describe what an information set is about by formally declaring topics, by establishing typed relationships among topics, and by linking the relevant parts of the information set to the appropriate topics. Since they can be in separate documents, and since they can work without changing the source information set, Topic Maps are superimposed views applied from "above" the information set. A topic map expresses someone's opinion about what the topics are, and which parts of an information set are relevant to which topics. There is no limit to the number of topic maps that can be created above the same information set.

Topic maps can be merged such that the topics and associations from one map are combined with the topics and associations of another map to create a new map that represents the union of the knowledge in both maps. This allows independently captured knowledge to be combined in meaningful ways.

There are currently two standard syntaxes for topic map interchange: the original HyTime-based syntax, defined in ISO/IEC 13250, and the XML /Xlink-based syntax, defined in the XTM specification. Both syntaxes reflect the same fundamental abstract topic map model. These two syntaxes are being formally unified by the ISO committee responsible for the ISO/IEC Topic Map standard.

Topic Maps and XTM are similar in many ways to the W3C Resource Definition Format (RDF). There has been and continues to be a great deal of work to understand the relationship of these two standards to each other. All of this work is being done more or less in the context of the W3C's semantic Web activity.