A-E call numbers - Lower Level of McCabe (below the main floor)
F-K call numbers - Level 2 (above the main floor)
L-Z call numbers - Level 3
S McCabe Ref Books in the Reference section (example) are found on the main level of McCabe.
S McCabe + Oversize books (example) are shelved separately. They'll be on the same floor as the non-oversize books in their call number range (e.g. you'll find a +G book on the lower level).
S McCabe ++ Double oversize books (example) are all found on the 3rd level of McCabe.