An arithmetic expression containing symbolic parameters For MVP this could be limited to PInt and PParameter only. However, it would be useful to have a more general type definition so that functions that manipulate constraints, parameters, etc can be written in a more general way. The actual parameter value is customisable so that the same code can be used for int parameters (normal) and BigInt parameters (needed for constant values in N bit components). For MVP set 'PINT = int TODO: refactor this to use an enumeration DU for operators to reduce cases.