Typically, one CAM board consists of two halves, within each of which there is an evolution plane and a function plane for Moore neighborhoods, and either one single evolution plane-pair or else two independent evolution planes, for von Neumann neighborhoods. Inasmuch as the central cells of all the planes are available to the CAM update mechanism, some of the planes can exert a binary influence upon the choice of rules in the remainder.
If the selection plane is static, this means that some cells evolve by one rule set, the remainder by a second set. The selection plane itself could evolve, resulting in a dynamic process. The extreme case would be a formally defined composite automaton, but oftentimes very simple relationships suffice to get quite practical results.