Tracker 4.44
8.5: How to set sample numbers and note periods
There has to exist a separate automaton for each of the four channels
of a Protracker song. To have a sample number != 0 means to load
a number of parameters from the sample information:
Likewise, to have a note period different from 0 means to change the note period
immediately, except for the Tone portamento and
Tone portamento + Volume slide commands.