Reviews the position of C.I.S.P.R. limits for the protection of telecommunications from interference from ISM equipment, to clarify the roles of the CCIR and the C.I.S.P.R. in their collaboration in studies on the limits required for this purpose, to summarize the various proposals for methods of specifying limits and to derive from these a recommended method which will meet the objectives of C.I.S.P.R. and CCIR.