Would you believe I found the original manual at work.
(excuse the capitals, that's how it's printed in the manual)
First off, make sure you set the HOUSE CODE dial to the one and only House Code (A-P) that this unit will be addressing.
Second, turn it over and set the UNIT CODE group selector switch to either 1-8 or 9-16 to select which group of 8 modules this unit will be able to address (kind of like a Palm Pad). If you set it to 9-16, add 8 to the setting on the UNIT CODE slide switch (a) to calculate the actual addressed Unit Code.
TO SET TIME OF DAY:
1. Slide switch (a) to TIME OF DAY and press "SET TIME" keys (c) ("FAST/SLOW") to correct hours and minutes.
TO PROGRAM A UNIT FOR AUTOMATIC OPERATION:
1. Slide switch (a) to desired UNIT CODE.
2. Slide switch (b) to ON and press "SET TIME" keys to set desired ON time.
3. Press "DAILY" or "ONCE" or "SECURITY" to complete automatic ON program.
4. Slide switch (b) to OFF and press "SET TIME" keys to set desired OFF time.
5. Press "DAILY" or "ONCE" or "SECURITY" key to complete automatic OFF program.
It says the "SECURITY" key will make the ON or OFF happen at a random time between the time you set and 32 minutes later.