1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 “ TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-%!.3G0G0/ that, moreover, it is an advantage,wherever possible, to have notations that have been universally adopted;(b) that CMV is collaborating with Technical Committee No. 25 of the IEC,recommendsthat in
2、 their mutual relations the ITU and its permanent organs and Administrations and recognized privateoperating agencies use in all languages, wherever possible, the letter symbols and the notations recommended by theInternational Organization fon Standardization (ISO) and the International Electrotech
3、nical Commission (IEC) torepresent the physical quantities and the mathematical operations.Note References of relevant publications (updated in 1988).ISO Standard 31: “General principles concerning quantities, units and symbols”Parts of ISO Standard 31 of greatest interest for telecommunications:0 (
4、General principles)I (Quantities and units of space and time)II (Quantities and units of periodic and related phenomena)V (Quantities and units of electricity and magnetism)VI (Quantities and units of light and related electromagnetic radiations)VII (Quantities and units of acoustics)XI (Mathematica
5、l signs and symbols)IEC Publication 27: “Letter symbols to be used in electrical technology”27-1 General (1971 Edit. 5, with 1974 Amend. 1 and 1977 Amend. 2) (1983 Amend. 4, including 1981 Amend. 3)27-1A (1976) (Time-dependent quantities)27-2 (1972) (Telecommunications and electronics)27-2A (1975) (
6、First supplement: waveguide propagation; scattering matrix and transfer matrix; static convectors; automatic control science and technology)27-2B (1980) (Second supplement: linear n-port networks)27-3 (1974) (Logarithmic quantities and units) (see CCIR Recommendation 574)27-4 (1985) (Quantities to be used for rotating electric machines)See also IEC Handbook Letter Symbols (1983) and the Directives applicable to the work of the IEC on letter Symbols (1986)._1)A similar text will be submitted to the CCIR as a revision of Rec. 608.
