(RANKIN) of equivocation information (1-: ) and interaction information (M). The method is described in the present paper for I: and in a previous paper (Orloci, 1976) for M. The results presented in this paper suggest that for Species Rank order Information Percentage of total* species to be weighted according to their suitability to I. M I M r M characterize isolated groups of releves in a phytosociolo 5 7 54.15 2.31 17.97 0.82 gical table, the equivocation information may serve as a 9 5 49.86 23.19 16.55 8.22 3 3 9 47.79 0.56 15.86 0.20 suitable weight. The appropriate formulations are...