I mean, say we want to show how we can implement an OR gate in terms of a NAND gate. If we write in Polish notation, then we've suggested that the circuit takes the gates before the inputs. If we write it in infix notation, we've suggested a mix. But if we write ppDqqDD, then we've suggested that we have the input 'p', then 'p' again, then those pass through NAND in the circuit, 'q', then 'q' input again, then they pass through NAND, and finally the result of what the previous NANDs found passes through the final NAND.
So doesn't an expression in Reverse Polish Notation tell us exactly how a circuit behaves? Or does it only describe the behavior of some circuits? Which types of circuits, if any, does RPN describe in this way?