In a Nutshell

A very compact illustration of all relationships within the TMDM was created by Marcel Hoyer.

Single arrows mean that there’s a simple reference from one object to another while double arrows refer to sets of references.
This illustration makes two concessions to TMAPI users: A TopicMap according to TMDM does not have a locator. This is just needed to address the TopicMap object within TMAPI. Furthermore, TMDM Topics don’t have IDs, these are only there for simplified handling in TMAPI. The TMDM in a Nutshell was originally published at

More Information

For programmers, many software libraries, called Topic Maps engines are available to use, some of which are part of complete knowledge management solutions.

Students and academics will find the Topic Maps Library useful. It includes many publications, a glossary, information about standards and more.

Many companies offer commercial services and/or consulting around Topic Maps products. The list of sponsors of TMRA is a good place to look for them. The Topic Maps Projects list gives some starting points, too.

The Standards are available through ISO. The latest versions can also be obtained at The most prominent standard is the Topic Maps Data Model which uses XTM 2 and CTM as serializations.