the cuts vary in number and location by the particular firearm. usually it's two vertical cuts (aometimes specified to be on an angle) and sometime a horizontal cut is added.
minimum material removal is 1/4" per cut and a torch is the specified instrument de jour.
the regs per firearm are "rulings" made by the atf, and they also change from time to time (witness the fal and 1919 ruling changing last january).
the falfiles board can be searched for pics/regs on the fal and 1919.