_     Rec. X.220

                                  Fasc’culo VI.7 - Rec. X.220     _
                                 
                             SECTION 3
                                 
                      PROTOCOL SPECIFICATIONS



Recommendation X.220
Fasc’culo VI.7 Ð Rec. X.220
                                 
      USE OF .i.;X.200-SERIES PROTOCOLS IN CCITT APPLICATIONS
                                 
                         (Melbourne, 1988)

     The CCITT,

considering

      (a)   that Administrations in many countries are implementing
a variety of telecommunications services;

      (b)    that  these services may be carried on  a  variety  of
networks;

       (c)    that  users  of  these  services  desire  a  unifying
architecture for the applicable protocols;

      (d)   that such an architecture is provided by Recommendation
X.200   which   defines  the  Reference  Model  of   Open   Systems
Interconnection for CCITT Applications;

       (e)     that  a  number  of  protocols  conforming  to  this
architecture are defined in the X.200 Series of Recommendations and
in other Recommendations,

unanimously declares

       that  for  CCITT  Applications,  the  functional  suites  of
protocols,  which involve the use of protocols in the X.200  series
of Recommendations, are summarized in this Recommendation. Details,
as  well  as  any  conformance requirements, are contained  in  the
relevant Recommendations.

      A  growing  number  of  data terminal  equipments  are  being
designed  to support more than one CCITT service and/or  are  being
designed to be capable of being connected to more than one type  of
network. In order to facilitate the design of such equipments,  the
various  OSI protocol suites involving use of the X.200  series  of
Recommendations are documented herein.

      These  protocol suites are depicted in Figure 1/X.220,  which
portrays  the  protocols according to the seven layers  defined  in
Recommendation  X.200. The CCITT Applications covered  are  Message
Handling   Systems   (MHS),   Directory,   Teletex   and   Document
Architecture  Transfer and Manipulation. The networks  covered  are
PSPDN,  CSPDN, PSTN and ISDN. The intent is to give a general  view
of  the set of protocol suites in a single figure, while relying on
the  other  Recommendations referenced  to  provide  the  necessary
additional details.


                                 
                                 
                                 
                                 
                          FIGURE 1/X.220