Thre different types of serialization formats are standardized by ISO:

  • XML Topic Maps (XTM) and
  • Compact Topic Maps (CTM)
  • Canonicalization (CXTM)

XTM exists in three versions:

There’s currently only one version of CTM

CXTM is an export-only format which allows binary file comparisons.

Community Standards

Besides the official standards, some other formats where developed to serve different purposes:

  • TM/XML
  • JSON Topic Maps (JTM)
  • LTM (superseeded by CTM)
    … and more.


The TMAPIX suite offers import and export of many formats for TMAPI-based engines.

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.