wSEQ is a software sequencer for the windows platform. It's notation is based on the soundtracker standard which was introduced on the Commodore Amiga. Soundtracker was a composition program using audio samples as sounds.
The advantage of the soundtracker notation in opposite to the nowadays used rollbar/pianobar notation is, that fast inputs can be made via the computer keyboard without the use of the mouse or a midi keyboard. This is especially interesting for composers that do not play a key instrument.