Just as an aside, now that Polaroid has axed all of their films, "gram" should be labeled just "g" to avoid confusing with the similar "grain", which used to be abreviated with a similar "gn." all the time. To avoid confusion, one is "g" and the other is "gr."
I see gram labeled "gr." all the time though too, so, ick, what a mess.
As for quarts, as there is a liquid & dry U.S. version, and an Imperial one, it is best to label these U.S. or Imperial.
Don't even go there with teaspoons, tablespoons, or coffeespoons! ;-)