PRESSURE C     [ca force + press]     P.c - P.ca = ca force
P.c is the pressure variable in the ca force.  P.c is determined by the stiffness of the ca stack.  A stiffer ca stack will produce HIGHER P.c, resulting in a greater pressure drop and higher ca force. P.ca is dependant on the nitrogen charge and does not fluctuate with valving changes. Consider P.c as the primary pressure which can be regulated with the ca shim stack and clickers.  The pressure difference derived from  (P.c - P.ca)  is used to calculate ca.force.
First some background. Pressure in the rebound chamber (P.r) is determined by the stiffness of the mv comp stack. On the comp stroke, the piston is driven into the shock body. Pressure on top of the piston (P.c) increases.