INTERNATIONAL TELECOMMUNICATION UNION
TELEGRAPH AND TELEPHONE
GENERAL ASPECTS OF DIGITAL
SYNCHRONOUS FRAME STRUCTURES
USED AT PRIMARY AND
SECONDARY HIERARCHICAL LEVELS
The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988).
Recommendation G.704 was prepared by Study Group XVIII and was approved under the Resolution No. 2 procedure on the 5th of April 1991.
1) In this Recommendation, the expression “Administration” is used for brevity to indicate both a telecommunication Administration and a recognized private operating agency.
2) A list of abbreviations used in this Recommendation can be found in Annex B.
ã ITU 1991
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SYNCHRONOUS FRAME STRUCTURES USED AT
PRIMARY AND SECONDARY HIERARCHICAL LEVELS
(Malaga-Torremolinos, 1984; amended at Melbourne, 1988, revised 1990)
This Recommendation gives functional characteristics of interfaces associated with: