MO3

MO3 is a tracker module file format developed by Ian Luck for the BASSMOD engine. MO3 files contain samples encoded in the MP3 or Ogg Vorbis formats, rather than straight PCM samples. This results in reduced file size for the module, while maintaining almost identical audio quality. Lossless audio encoding is also supported, for samples that do not compress well with lossy encoding.

The format's name is a portmanteau of MOD and MP3. Despite the name, five other tracker formats are supported besides MOD: Scream Tracker 3 (S3M), FastTracker 2 (XM), Impulse Tracker (IT), OpenMPT (MPTM) and MultiTracker (MTM).