Then ...
Bob Jewett said:
Draw an outline around the outside of the traiangle -- the whole thing. Any ball that is overlapping that outline or within the outline is considered to be interfering with the rack. Use pencil if you want.
The size of the outline varies with the kind of triangle you use. Some plastic ones have lips on only one side, and then I suppose you have to decide which end to have up when you mark the outline.
I'm startled that anyone would have tried to mark the inside of the triangle. The first time the last ball is 1/16 of an inch from the racked balls, it will be clear why that can't work (unless you are willing to mark and respot the 15th ball, which is never done).
If you mark the outside of the rack, considering some wood racks are
fairly thick, then a 15th ball could be outside of the actual balls racked
and not get to stay there which would change the game since if it
stayed there could be a break shot and allow a player to continue
running the balls. Bob, I don't know about you, but I am old school,
and we would, when close, would lick our finger, mark the cloth with
a wet spot at the base of the 15th ball, rack the other 14, and then
try to determine if the 15th ball would spot back exactly as it was
before without running into the racked balls. If not, it went to the head
spot, if it did, it stayed there. I could be wrong about this, but I believe
in the old days, that a referee in a staight pool tournament did it this same
way as I described. I played most of my straight Pool in early 60's.