CONTENTS

 1     Scope
        1.1     General
        1.2     Relationship to other international standards and Recommendations
 2     Definitions
 3     Abbreviations
 4     Overview of multiplexing operation and services
        4.1     General
        4.2     Overview of the Service User (SU)
        4.3     Overview of the Multiplexing Function (MF)
        4.4     Communication between the SU and the MF
 5     Multiplexing platform and frame structure
        5.1     Basic frame structure and fields
        5.2     Format conventions
        5.3     Invalid frames
        5.4     Frame abort
        5.5     Interframe time fill
 6     Elements of procedure and field formats
        6.1     Address field format
        6.2     Control field format
        6.3     Control field parameters and associated state variables
        6.4     Frame types
        6.5     Use of timers
 7     DLC procedures
        7.1     Establishment of a data link connection
        7.2     Information transfer
        7.3     Orderly release of a DLC
        7.4     Disconnected state
        7.5     Collision of unnumbered commands and responses
        7.6     Exchange identification procedures
        7.7     Loop-back test
 8     Information transfer modes
        8.1     Error recovery mode
        8.2     Unacknowledged non-error recovery mode
        8.3     Transfer of user-control information
        8.4     Additional information-transfer procedures
 9     System parameters of the multiplex function
        9.1     Acknowledgement timer (T401)
        9.2     Maximum number of retransmissions (N400)
        9.3     Maximum number of octets in an information field (N401)
        9.4     Window size (k)
        9.5     Reply delay timer (T402) – Optional
        9.6     Inactivity timer (T403) – Optional
        9.7     DLCI values
        9.8     Operational mode
10     Negotiation of optional procedures
Annex A – Optional suspend/resume operation
        A.1     Introduction
        A.2     Abbreviations
        A.3     Operation of suspend/resume
        A.4     Error conditions with suspend/resume
        A.5     Interoperability of suspend/resume with basic frame format
        A.6     Error-recovery performance
Annex B – Procedures and encoding for conveying break signals
        B.1     Procedures for transfer of break signals
        B.2     Encoding of break information
Annex C – Parameter values and optional procedures for operation with Recommendation V.70
Appendix I – Data retransmission
        I.1     Introduction
Appendix II – Additions for “Unnumbered information with header check” feature
       II.1     Introduction
       II.2     Abbreviations
       II.3     Changes for UIH feature
Appendix III – Cross-reference between Recommendations V.76 and V.42