Although they aren't in the rules (I don't think!) they're officially defined in this WFTDA release:
Questions could take the form either of
-an image of the signal being performed/a description of the signal, followed by options on what the signal represents, or;
-a statement of the event being signalled with the possible answers being descriptions of various actions.
I don't know if it'd be necessary for more experienced players, but I think it would be really helpful for those of us just starting out! There are so many of them and during jams these things tend to happen faster than I can keep up with.