Possibly OT: How to tell if an option ROM hooks INT19 / supports boot?

Is there a way to tell if an option rom for a device thinks it’s bootable? I.e. if I looked at the PXE option rom, how would I tell whether it hooks int19 to take control of boot, and if so where would I need to look in other roms? I haven’t had much luck reading up on the subject…

R