In FBD, instruction references can retain the parameter assignments of the reference that is being overwritten. All Negate and Immediate parameter settings are retained as well. The following conditions must be met:

·The editor must be in Overstrike Mode and the instruction must be placed directly over an existing instruction.

·The instructions must have the same number of parameters in each parameter region.

In this example, Divide Real retains the parameter assignments of Multiply Real. These box instructions each contain one logic flow input parameter, one logic flow output parameter, no box top parameter, two input parameters, and one output parameter. Note that the Negate of the first logic flow input is retained, as well as the Immediate on the logic flow output.

Here, Count Up/Down does not retain the parameters of Count Up. The instructions do not have the same number of logic flow input parameters.