XM (file format)

XM, standing for "extended module", is an audio file type introduced by Triton's FastTracker 2. XM introduced multisampling-capable instruments with volume and panning envelopes, and basic pattern compression. It also expanded the available effect commands and channels, added 16-bit sample support, and offered an alternative frequency table for portamentos.

XM is a common format for many chiptunes.

The file format has been initially documented by its creator in the file XM.TXT which accompanied the 2.08 release of FastTracker 2, as well as its latest known beta version: 2.09b. The file bears the header "The XM module format description for XM files version $0104.", is therein attributed to Mr.H of Triton (Fredrik Huss) and has been written in 1994. The contents of the file have been posted on this article's Talk subpage for reference.

This documentation is however said to be incomplete and insufficent to properly recreate the behaviour of the original program. The Milky Tracker project has however put a lot of effort in expanding and completing the documentation of the XM file format, in an attempt to faithfully replicate not only the behaviour of the original software but also its quirks. Their documentation of the XM file format is available on the project's GitHub repository.