Recommendation B.191) 
ABBREVIATIONS AND INITIALS USED IN TELECOMMUNICATIONS
	The CCITT,
considering
	(a)	the rapid increase in the number of abbreviations and initials used in the texts of the CCIs;
	(b)	that it is sometimes difficult to find the precise meaning of an abbreviation or acronym appearing in a text of the CCIs,
recommends
	(1)	that, with the exception of abbreviations frequently used in telecommunications, abbreviations and acronyms should not be used in the texts of the CCIs unless they make the text easier to read, i.e. when an abbreviation may be used several times in the same text;
	(2)	that, with the exception of abbreviations frequently used in telecommunications the first time an abbreviation is used in a particular text its full meaning should be given, either in the body of the text or in a footnote;
	(3)	that at alphabetical list of the abbreviations used in the CCI volumes should be published either at the end of each volume or in a separate fascicle2), 3) 
	(4)	that for abbreviations specific to certain fields, the Administrations, CCI Secretariats and other participants in the work of the CCIs should use the abbreviations which appear in the publications listed in Appendix I.
APPENDIX I
(to Recommendation B.19)
References to lists of specific abbreviations
I.1	Frequency and wavelength bands
	See Recommendation B.15.
I.2	Alphabets, codes, routing codes and identities
	See the relevant CCITT Recommendations (Index of the Blue Book, Fascicle I.4).
I.3	Codes contained in the Radio Regulations
I.3.1	Designation of emissions: Article 2.
I.3.2	Symbols for the various types of antenna: Appendix 2, Section III.
I.3.3	Q code, general section (QRA to QUZ): Appendix 13, Section I.
I.3.4	Miscellaneous abbreviations: Appendix 13, Sections I and II.
I.3.5	SINPO and SINPFEMO codes: Appendix 15.
I.4	Abbreviations used by the ITU for the names of countries
	See the Preface to the International Frequency List, Table I. (Different abbreviations have been approved by ISO.)
I.5	Acronyms of international organizations involved in telecommunications
	See the ITU “List of Adddresses”, § 3.
I.6	Symbols and names for units
I.6.1	Recommendation B.3 gives the sources to be used. This Recommendation refers to IEC Publication 27 and to ISO International Standards 31 and 1000.
I.6.2	Recommendation B.14: Terms and symbols for information quantities in telecommunications.
I.6.3	Recommendation B.15: (Note 2) – Frequency unit.
I.6.4	Recommendation B.12: Use of the decibel and the neper in telecommunications.
I.6.5	Recommendation B.18: Traffic intensity unit.
I.7	Letter symbols
	Recommendation B.1: “Letter symbols for telecommunications” provides guidelines to be followed to simplify the reading of documents dealing with telecommunication techniques; it refers to IEC Publication 27 and to ISO International Standard 31 for letter symbols to represent physical quantities and mathematical operations.
I.8	Chemical symbols
	See the table published by the International Union of Pure and Applied Chemistry (IUPAC).