I have taken a look at the fiche, and assuming that the shock is pictured as it sits in the bike, the following should be true.
The knob at the top of the shock is your rebound clicker. This controls a needle that sits inside of the shock shaft. That needle controls the amount of bleed through the hole you'd see in the center of the shaft if/when you disassemble it. It allows the fluid to enter the shaft on the rebound side through holes in the side of the shaft, and dump onto the compression side.
The Knob(s) on your reservoir control(s) compression. It controls how fast the fluid can enter the reservoir as it's displaced under compression.
One will affect the other to some degree, but they will have the most effect on the condition for which they're named.
Odd to see a shock mounted upside down, but those were some crazy transitional years.
