CEMvelope is based on the legendary ADSR section of the Sequential Circuits Pro-One monosynth, with minor adaptations to integrate it into Euro format. Smooth and snappy!
It has a gate input as well as a trigger input, the trigger input works in conjunction with the gate input for multiple triggering from a suitable controller device. For regular use, you can just use a gate input to access all features. Or use a gate input as well as patching additional modulation (an LFO perhaps) via the trigger input. Please note that the trigger input will not work in isolation, but only when the gate input is high.