A @[email protected] for which the expression for the @[email protected] of a reactant (or @[email protected] of a product) involves rate constants of more than a single @[email protected] Examples are '@[email protected]' (where rate constants of two opposed chemical reactions are involved), '@[email protected]' (for which the @[email protected] of any reactant is governed by the rate constants relating to several @[email protected] to form different respective products from a single set of reactants), and @[email protected]