A survey is given of results about coherence for categories with finite products and coproducts. For these results, which were published previously by the authors in several places, some formulations and proofs are here corrected, and matters are updated. The categories investigated in this paper formalize equality of proofs in classical and intuitionistic conjunctive-disjunctive logic without distribution of conjunction over disjunction. Mathematics Subject Classification (2000): 18A30, 18A15, 03G30, 03G10, 03F05, 03F07, 03B20