Recommendation B.141)
                                   TERMS AND ABBREVIATIONS FOR INFORMATION
                                      QUANTITIES IN TELECOMMUNICATIONS
               The CCITT,
         considering
               (a) that in telecommunications data transmission is more  and  more  widely
         used;
               (b)  that  the  ISO  is  the  international  organization  concerned   with
         standardization in the field of data processing;
               (c) that IEC Technical Committee No. 25 has requested  the  CMV  to  assist
         with the  definition  of  letter  symbols  for  terms  and  units  used  in  data
         communication,
         recommends
               (1) that the CCIs should use the terms "bit", "baud", "shannon", "byte" and
         "N-bit byte" with the  definitions  established  by  the  ISO  and  the  ITU  and
         appearing in Annex A;
               (2) that the term "bit" is synonymous with "binary digit" and is also  used
         in the letter symbol for this unit; the term being an abbreviation of the English
         term "binary digit" and being adopted also in French and Spanish;  for  multiples
         of this unit and for derived units the letter symbols kbit, Mbit,  kbit/s  should
         be used;
               (3) that the unit "baud" should have as its letter symbol Bd with  possible
         multiples of kBd and MBd;
               (4) that the unit "shannon" should have as its letter symbol Sh;
               (5) that for the terms "byte" it is the task of  the  ISO  to  provide  the
         letter symbol it judges to be necessary.  In  the  meantime  this  term  and  its
         multiples should be written in full in the documents and texts of the  CCIs.  For
         example 10 kilo-bytes, 1 mega-byte. The term "N-bit byte" has no multiples.
                                                   ANNEX A
                                      (to Recommendation B.14)
         A.1    binary digit, bit
                   F: ‚l‚ment binaire, bit
                   S: digito binario, bit
               A member of a set of two elements commonly used to represent information.
               Note - In the interest of clarity, it is recommended that  the  term  "bit"
         shall  not  be  used  in   two-condition   start-stop   modulation   instead   of
         "unit-element".
         A.2    binary digit rate, bit rate
                   F: d‚bit binaire
                   S: velocidad binaria
               The number of binary elements transferred in a  time  interval  divided  by
         that time.
               Note: - The binary digit rate is expressed in bits per second  (bit/s)  and
         multiples of this unit.
         A.3    baud (symbol: Bd)
                   F: baud (symbole: Bd)
                   S: baudio (s¡mbolo: Bd)
               The unit of modulation rate in telegraphy and  data  communication  or  the
         unit of line digit rate in digital transmission; when expressed in terms of  this
         unit, the modulation rate or  line  digit  rate  equals  the  reciprocal  of  the
         duration in seconds of the shortest signal element or of the unit interval  in  a
         digital signal composed of signal elements of constant duration.
               Example - If the duration of the unit  interval  is  20  milliseconds,  the
         modulation rate is 50 bauds.
         A.4    shannon
                   F: shannon
                   S: shannon
               A unit of logarithmic measure of information equal to the decision  content
         of a set of two mutually exclusive events expressed as a logarithm to base two.
               Example: The decision content  of  a  character  set  of  eight  characters
         equals 3 shannons (log2 8 = 3).
         A.5    byte octet, 8-bit byte
                   F: octet
                   S: octeto (byte)

         1) A similar text will be submitted to the CCIR as a revision of Recommendation 607-1.



         Fascicle I.3 - Rec. B.14            PAGE1

               An ordered set of 8 binary digits operated upon as an entity.
         A.6    n-bit byte
                   F: multiplet n-uplet
                   S: multibit n-bit
               An ordered set of a specified number of binary digits operated upon  as  an
         entity.
               Note - This definition is compatible  with  the  definition  of  ISO  (Data
         Processing - Vocabulary, Part 4: Data Organization).





























































         PAGE2      Fascicle I.3 - Rec. B.14