The CGS116 is based on the Serge Extended ADSR. In addition to the usual Attack, Decay, Sustain, Release envelope, it has an adjustable Delay at the beginning of the envelope. All timings and the Sustain level can be voltage controlled. The envelope can be linear or exponential, or linear with an exponential attack. There is also a Master CV input that allows all timings to be reduced at once. When controlled by the same voltage as being used for VCO pitch, this allows for shorter envelopes for higher frequencies, as happens in acoustic instruments.
CGS116 Datasheet and Build Guide