Protocol specification, testing and verification, XII : proceedings of the IFIP TC6/WG6.1. twel[f]th International Symposium on Protocol Specification, Testing and Verification, Lake Buena Vista, Florida, U.S.A., 22-25 June, 1992 - IFIP TC6/WG6.1 International Symposium on Protocol Specification, Testing; Verification (North-Holland, 1992)