In the National Puzzlers' League rebus puzzle, a group of letters or other symbols, called a rubric, clues a word or phrase. For example, the rubric XCY clues chiromancy with the reading 'chi, Roman C, Y'. In a phonetic rebus, the sound of the reading is involved: for example, the rubric P clues rhopalic with the reading 'rho, pal, I see'. In an enigmatic rebus, something beyond what is visible in the rubric must be inferred, like the missing ST in the rubric AIN L, which clues stainless steel with the reading 'STAIN less S, tee; L'. In a reversed rebus, or suber, the reversal of the answer is clued.
Cohen, Philip M.
Word Ways: Vol. 12
, Article 4.
Available at: http://digitalcommons.butler.edu/wordways/vol12/iss3/4