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, written in 1994 and attributed to Mr. H of Triton (Fredrik Huss), bears the header "The XM module format description for XM files version $0104." 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 insufficient to properly recreate the behaviour of the original program. The Milky Tracker project has put a lot of effort into 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.