In reply to dave_59:
No, I am definitely not thinking of a port. I mean a parameter that needs to be successively updated in each module.
An analogous example of what I am trying to do would be something like fixed point mathematics. At each stage of processing, the data path width must grow according to the math that is performed in each module in the pipeline. For example, if I have two input arguments to a block that is performing addition, and those inputs are 2 bits wide, the output must have 3 bits to contain the result. So the parameter representing the width of the inputs must be modified and potentially passed out of the addition module for use in the next stage of processing.
What I am actually doing has nothing to do with this example, but fixed point is much easier to explain. I want to be able to modify a parameter at each stage in the design and pass that modified parameter out. But there is not any physical wire or bus width that is changing, only a parameter that relies on the previous value in the previous module. Right now I am doing this all manually, but it is very error prone.
Does that help explain the problem?