This music module has 4 channels of pattern data. Depending on the format used, more channels may be played simultaneously.

Heimdall is an action-adventure computer game developed by a team called The Eighth Day and published by Core Design for DOS, Amiga and Atari ST in early 1992.

More information at Wikipedia and Hall of Light.

MOD is the tracked music format used by ProTracker and many compatible tracker applications. This tag also covers variants of the MOD format with identical file structure but more than four channels.