Welcome to the forum and this issue is not a strong suit for me but a couple of observations. A zero tolerance is impossible to achieve. That would depend on the measuring instruments involved. Are we talking a wooden rule, a micrometer, a MMC, a microscope, and scanning electron microscope, and Atom watching thingy that IBM used to write their initials in Atoms?
Soo if your customer has zero tolerance on the drawing I suggest you send it back to them with a "get real" kinda statement.
Next, as a young draftsman many years back it was hammered into me to always put "Never assume, if in doubt ask" on all drawings (before pre-printed drawing sheets, yes, I am, that old). I suggest you take this advice and ask the customer.