WPCL 2BJ|x H   X  6p&6p&   HH `(#   c4 P Fascicle I.3 - Rec. B.1 PAGE1   HH  c4 P PAGE2 Fascicle I.3 - Rec. B.1  HH Hp P X`h!(# X  8O  c4 P PART IV 8CSERIES B AND C RECOMMENDATIONS 8FSERIES B RECOMMENDATIONS 8I Means of expression Recommendation H(p P X`h!(#( No.p   X%%**//`449Title H(p P X`h!(#( B.1Letter symbols for telecommunications ( B.3Use of the international system of units (SI)  H ( B.10Graphical symbols and rules for the preparation of documentation in telecommunications ( B.11Legal time; use of the term UTC ( B.12Use of the decibel and the neper ( B.13Terms and definitions  H ( B.14Terms and symbols for information quantities in telecommunications ( B.15Nomenclature of the frequency and wavelength bands used in telecommunications ( B.16Use of certain terms linked with physical quantities  H ( B.17Adoption of the CCITT Specification and Description Language (SDL) ( B.18Traffic intensity unit ( B.19Abbreviations and initials used in telecommunications Hp P X`h!(#Ђ Recommendation B.1  c4 P 1I  HH 1) c4 P  A similar text will be submitted to the CCIR as a revision of Rec. 608. )  c4 P  G c4 P LETTER SYMBOLS FOR TELECOMMUNICATIONS  c4 P  The CCITT, considering  (a)pthat in order to simplify the reading of documents dealing with telecommunication technique, it is essential to use simple notations in a homogeneous system and having well-defined meaning; that, moreover, it is an advantage, wherever possible, to have notations that have been universally adopted;  H  (b)pthat CMV is collaborating with Technical Committee No. 25 of the IEC, recommends  that in their mutual relations the ITU and its permanent organs and Administrations and recognized private operating agencies use in all languages, wherever possible, the letter symbols and the notations recommended by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) to represent 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:   0p (General principles)   Ip (Quantities and units of space and time)  H   IIp (Quantities and units of periodic and related phenomena)   Vp (Quantities and units of electricity and magnetism)  Hx   VIp (Quantities and units of light and related electromagnetic radiations)   VIIp (Quantities and units of acoustics)   XIp (Mathematical signs and symbols)  H  IEC Publication 27: "Letter symbols to be used in electrical technology"  H Hp X`h!(# hph     p H 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)  H  hph     p H 27-2A (1975) (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)  H  27-4 (1985) (Quantities to be used for rotating electric machines)  H Hp P X`h!(# See also IEC Handbook Letter Symbols (1983) and the Directives applicable to the work of the IEC on letter Symbols (1986).