I didn't stay in a Holiday Inn Express last night

but I believe " drilled " rotors are manufactured two different ways. One is when the rotor is cast the holes are part of the casting process. These are more costly to make and less prone to cracking and are not chamfered. The second way is after the rotors are cast they are then machined/drilled. Less costly but more prone to cracking so part of the drilling process also bevels the edge of the holes.