We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Matty F saying something like:
Because of the possibility of confusion - normally the convention is from the patient's /subject's /driver's viewpoint, but who knows what viewpoint has been used if a third party is reading it. The hard and fast naming of a part does away with the possibility of removing the wrong kidney, leg, eye, etc, - you'd think, anyway. Of course, that doesn't totally avoid the chance of total cockup, as happened here, when a surgeon removed a healthy kidney from a kid, leaving him with the bust one. This was in spite of the mother and somebody else spotting the error and mentioning it.