Comp and others you can ask ASA/USA umps and they will tell you it is an interpretation call and 6 umps in a room can have 6 different interpretations. I am just telling you what I have seen called on a consistent basis and the umps have used as the reason for calling the runner out immediately.
Experienced ASA/USA umps have been asked. Their names are Comp, MTR, CPEM...and probably some others in this thread, too. They have all said exactly the same thing.
As for interpretation, the quote of Supplement 34 F I posted above is pretty damn clear.