an example can be found on AMOSPro_Examples:Examples/H-7/Help_76.AMOS
Defines a sound ENVELope.
Set Envel wave,phase To duration,volume
wave = the number of the waveform,
phase = a phase number from 1 to 6
duration = length of the current step in units of a 50th of a second.
volume = the intensity of the note at the end of the phase. Allowable values range from 0 to 63.