S> A bijectivemap between two objectS which preServeS, in both directionS, any Structure under conSideration. ThuS a `group iSomorphiSm' preServeS group Structure an order iSomorphiSm (between poSetS) preServeS the order relation, and So on. USually it iS clear from context what Sort of iSomorphiSm iS intended. (1995-03-25)