I remember in the sequence where Sean Malto does a trick that was captioned as "nollie overcrooks". I mean I wondered as I looked at the sequence, because even on a round rail, his board was very parrallel to the rail (maybe dipping a tiny bit of the tail over the rail), and saw the footy in Pretty Sweet, that just sealed it for me.
Backside nosegrinds dont exist on round rails, only overcrooks. Just like how frontside overcrooks dont exist period, so its just "nosegrind". Which on rails, if frontside, just "Nosegrind" will get the picture, whereas saying just "Overcrooks" and people understand that its backside.