1. In a system having a plurality of individual heating or cooling units, each having a programmable control unit including a processor and memory associated therewith, the programmable control unit interfacing with a set of discrete elements that implement the prescribed heating or cooling of the individual heating or cooling unit, a process executable by the processors in at least two programmable control units comprising the steps of: controlling the heating or cooling to be performed by the heating or cooling unit through a control program common to the control program in at least the one other control unit, the control program being stored in the memory associated with the processor in each programmable control unit, the control program stored in the memory associated with the processor in each programmable control unit having a set of control variables identical to the control variables of the control program stored in the memory of the processor in the other programmable control unit, the control variables in each control program having program control values that vary from time to time as the control program is repeatedly executed by the processor; and accessing configuration data stored in the memory associated with the processor in each programmable control unit when communication of control values is to occur between the programmable control unit and the discrete elements that implement the prescribed heating or cooling, the configuration data comprising a set of first indicia corresponding to the control variables wherein each particular first indicia corresponds to a particular control variable, and a set of second indicia corresponding to the discrete elements that are actually present in the particular heating or cooling unit wherein each particular second indicia corresponds to a particular discrete element, and wherein the configuration data further comprises stored associations of said second indicia linked to respective first indicia whereby each second indicia is linked to a respective first indicia, said step of accessing configuration data comparing the steps of: using a first indicia to identify a linked second indicia corresponding to a particular discrete element when communication of a program control value is initiated by the programmable control unit; and using a second indicia corresponding to a particular discrete element so as to identify a linked first indicia corresponding to a particular control variable when communication of a control value is initiated by the particular discrete element.