Bob:
You can go in standing and not automaticly be illegal. If you alter the play it's a straight interference call not a FPSR. If you slide you must slide legally,then if you do anything illegal then the FPSR comes in. You are correct that it doesn't reguire alteration. I believe that was checked with McNeely and that was his ruling. Don't quote me on that but I'm pretty sure it was run by him.