[just another ref]

Can anyone tell me why there are questions on an officials' test which deal with language in the book and nothing else? First example that comes to mind
(I'm sure there are others) True or False: It is possible for an airborne shooter to commit a common foul. UHHHHH......lemme think.....mentally turning to that page.......TRUE! I got that one right on the test, which is the only reason for me to know this particular fact, is it not? I'm a little vague about the reason for the term common foul and its definition in the first place, as it is still very necessary to know all the details of each member of the set which is "common fouls." Am I overlooking something obvious? It wouldn't be the first time.