Tracker module format used by digital audio tracking programs; includes multiple tracks with notes that compose a musical score; notes are linked to sound samples, which are also included in the file.
Program(s) that open dsm files
Mac: CocoModX Windows: MODPlug Player; Media Player Classic (MPC); Nullsoft Winamp
Unix: XMMS
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/dsm
