Hi,
s-nadsr~ is not an ADSR envelope (but it is kind of similar). Like the s-env~ GOP abstration, it allows you to design a custom envelope by ctrl-clicking the envelope array to add new points. When triggered with midi note pairs, it will output the envelope up to the sustain marker for a note-on and after the sustain marker for a note-off. You can drag the sustain marker to any position inside the envelope.
http://mccormick.cx/viewcvs/*checkout*/s-abstractions/s-nadsr~.pd?root=svn http://mccormick.cx/viewcvs/*checkout*/s-abstractions/s-nadsr~-help.pd?root=svn
This abstraction has no dependencies except Pd 0.39 or higher.
You can check out the whole set of s-abstractions here: http://mccormick.cx/viewcvs/s-abstractions.tar.gz?root=svn&view=tar
Have fun!
Chris.