The Moog 993 Trigger and Envelope Voltages is simply a patch panel for the three 911 Envelope Generators, three 902 VCAs, and the 911A Dual Trigger Delay modules. The Moog description of this module is:
The Trigger and Envelope Voltage Panel is a signal routing module for S-triggers coming from one or two controllers. Lighted switches labelled "from 1" or "from 2" at the top of the panel connect the controller trigger outputs (when lighted) to the 911A Dual Trigger Delay. The lower three left hand column switches route the trigger signal as follows: top switch - to left 911 with no delay, center switch - to center 911 with delay set by top 911A delay unit (if any), bottom switch - to the right 911with delay set by the bottom 911A (if any). The right hand green switches connect the DC control voltages from the 911's to their respective 902 Voltage Controlled Amplifiers: Left to left, center to center, right to right. Any of these routes may be connected at the same time.
Almost two years passed between first inspection and test on this module.
I have not been able to find any schematics on this module but it is simply switch wiring to the rear connector.
Here is a photo of the switch wiring. There are three 100K 1% resistors wired in series with the green switches which route the 911 envelope generator control voltage to the 902 voltage controlled amplifier.