The four envelopes can be chained for creating a multi-stage envelope available at the Mix output. You can determine at which threshold if the decay stage the next envelope will be started. A bi-polar attenuator at each envelope determines if it wil be added normally or inverted to the mix.

The four envelopes can be chained for generating a complex multi-stage envelope, available at the Mix output. If is possible to determine a threshold at which decay level the next envelope will be fired. Each envelope can be added normally or phase inverted to the mix with a polarizer.
Each channel has a end-of-attack output which will generate a gate signal after the attack phase has been finished. The gate from the comparator which will fire the next envelope is available at the comparator output (CPx).