9.Proposed additions and revisions to Recommendation M.1050

    LINING-UP AN INTERNATIONAL POINT-TO-POINT LEASED CIRCUIT

       The first sentence of  1 of Recommendation M.1050  should  be
continued:

       "... in Recommendations M.1020 and M.1025) which are  provided  by
       analogue  transmission  systems  or  by  a  mixture  of   analogue
       and digital systems."

       The following text should be inserted under the heading  "2.1   National
sections":

       "When analogue access to  the  circuit  is  available  at  the  terminal
international centre the following tests should be performed regardless of whether the 
national section is provided by analogue circuit sections or a  combination  of
analogue, mixed and digital circuit sections."

       The following text should be inserted under the heading 
"2.2  International section":

       "When  analogue  access  to  the  circuit  is  available   at   terminal
international centres the following tests should be performed regardless of whether the 
international section is provided by analogue circuit sections or a combination of 
analogue, mixed and digital circuit sections."

       Add the following text after the first sentence of   3  lining  up  the
overall circuit:

       "It should be noted that satisfactory impulsive noise performance  on  a
circuit is unlikely to be achieved if the circuit is routed via a primary digital 
path on which the bit error ratio exceeds 1.10-6*. It is not intended that this 
digital parameter be measured."

       Add the following footnote to  3:

"*  This parameter is used provisionally and further study is required  to  assess
    whether other parameters (e.g. those in Recommendation G.821)  would  be  more
    suitable for relating the performance of transient analogue impairments to     the 
performance of the digital paths on which the circuits are routed."

       The present  3.8 of  Recommendation  M.1050  should  be  replaced  by  the
following:

"3.8   Total distortion (special quality circuits only)

       When the circuit includes any digital circuit  sections  a  measurement  of
total distortion should be made using an instrument complying with  Recommendation
O.132. Such a measurement will include contributions from quantizing distortion, random 
noise, harmonic distortion and single tone interference. The minimum  signal/total
distortion ratio is given in Recommendations M.1020 and M.1025. However,  if  this
minimum ratio is satisfied it should not be assumed that all the parameters  which
contribute to the measurement are satisfactory. The total distortion measurement is not 
a substitute for the individual measurements specified in this Recommendation."

       Under the heading "4.1  National sections" insert the same  text  as  given
above for  2.1. Similarly under the heading "4.2  International section" insert the 
same text as given above for  2.2.

       The same text and footnote given for  3 of this Recommendation  should  be











added to the end of the  first  paragraph  under  "4.1.4.   Other  characteristics
(special quality circuits)".

       The same text and footnote given for  3 of this Recommendation  should  be
added to the end of the  second  paragraph  under  "4.2.4   Other  characteristics
(special quality circuits)".

       As a consequence of the above-mentioned changes the following text  has  to
be inserted under the headings of  2.2 and  4.2:

       "When analogue access to the circuit is available at the terminal
       international   centres   the   following   tests   should   be   performed
       regardless  of  whether  the   international   section   is   provided   by
       analogue  circuit  sections   or   a   combination   of   analogue,   mixed
       and digital circuit sections."

       The title of  3.11 should be changed to:

"3.11  Harmonic and intermodulation distortion (special quality circuits only)"

       A new second alinea should be introduced to  3.11 of the  Recommendation
as follows:

       "Alternatively,  by  bilateral  agreement  between   administrations,   a
measurement of second and third order intermodulation products using an instrument 
complying with Recommendation O.42 should be performed. The limit is for further 
study."

       The following amendments should be made to the second line  of    10  of
Recommendation M.1050:

       "If there is a  breakdown  or  planned  interruption  of  a  transmission
system, rerouting should be carried out as far as possible at group, supergroup or 
digital link level. This ... distortion. When such a rerouting of transmission links 
cannot be effected ... should be chosen, in particular with regard to the number 
of FDM carrier sections and the relative number of analogue and digital  circuit
sections. The procedure ...".