There are actually four envelope types. The bandwidth one in SubSynth has identical controls to the frequency envelope.
A.val Attack target value - amplitude only
A.dt Attack time
D.val Decay target value - filter only
D.dt Decay time - not frequency or bandwidth
R.dt Release time
R.val Release target value - not amplitude
Stretch Anticlockwise envelope is shorter on lower pitch notes and vice-versa
L Linear - amplitude only
frcR Forced release
The 'E' button opens the graphical window showing the overall envelope shape, where it is then possible to set freemode.
Freemode
This window shows a freemode enabled envelope. This is where all the normal controls have been assigned to fully editable target points. Not only that, but you can add points up to a maximum of 40. This allows you to develop extremely detailed and expressive envelopes.
The yellow vertical is the sustain/release point, and you can have new points both sides of it.
Freemode Enables or disable freemode behaviour
Add point Creates a new point before the highlighted one (there must be one highlighted)
Delete point Removes the highlighted point. There is a minimum of 3.
Sust (sustain) The point that is to be regarded as the sustain point. Zero gives no sustain.