CONTENTS

�1���� Scope
�2���� References
�3���� Terms and definitions
�4���� Abbreviations
�5���� Convention
�6���� Description of services
������� 6.1���� General
������� 6.2���� Service parameters
�7���� Architecture of the protocol
������� 7.1���� Service provided by the underlying layer
������� 7.2���� Link Flow Control
������� 7.3���� Link set-up
������� 7.4���� Link acknowledgement
������� 7.5���� Multiplexing
������� 7.6���� VC sequence and retransmission control
������� 7.7���� VC-flow control
���� ���7.8���� VC segmentation and reassembly
������� 7.9���� VC signalling
�8���� Description of the DTE/DCE interface (physical layer)
�9���� Coding of frames and packets
������� 9.1���� General
������� 9.2���� Description of frames
������� 9.3���� Description of packets
������� 9.4���� Meaning of the frame and packet fields
������� 9.5���� Coding of the Type field
10���� Link and VC-level procedures
������ 10.1���� Identification of the link connection
������ 10.2���� Generic status request procedure
������ 10.3���� Future upgrades with upward compatibility
������ 10.4���� Segment definition
������ 10.5���� Flow control at the link layer
������ 10.6���� Link set-up and disconnection
������ 10.7���� Procedure for positive and negative acknowledgements of PDU
������ 10.8���� Error correction
������ 10.9���� Multiplexing / demultiplexing
����� 10.10���� Numbering of packets at the VC layer
����� 10.11���� Re-ordering of data packets
����� 10.12���� Flow control at the VC layer
����� 10.13���� Data transfer
����� 10.14���� Interrupt procedure
����� 10.15���� Reset of a virtual circuit
11���� Signalling coding
������ 11.1���� Message functional definitions and contents
������ 11.2���� General message format and information elements coding
������ 11.3���� Addressing
������ 11.4���� Handling of coding errors
12���� Procedures for permanent virtual circuit service
13���� Signalling procedures for switched virtual circuits
������ 13.1���� Set-up and clearing procedures
������ 13.2���� Procedure for restart
������ 13.3�� ��Effects of clearing and restart procedures on transfer of packets
14���� Procedures for user facilities
������ 14.1���� Incoming calls barred
������ 14.2���� Outgoing calls barred
������ 14.3���� Packet size negotiation facility
������ 14.4���� Assured / non-assured data transfer negotiation facility
������ 14.5���� Throughput negotiation facilities
������ 14.6���� Closed user group related facilities
������ 14.7���� Fast select
������ 14.8���� Reverse charging
������ 14.9���� Reverse charging acceptance
����� 14.10���� Local charging prevention
����� 14.11���� Network User Identification (NUI) related facilities
����� 14.12���� Transit network selection related facilities
����� 14.13���� Hunt group
����� 14.14���� Call redirection and call deflection related facilities
����� 14.15���� Called line address modified notification
����� 14.16���� Transit delay selection and indication
����� 14.17���� Alternative addressing facilities
Annex A � Additional information for interworking between X.25 and X.45 protocols
������� A.1���� Throughput mapping
������� A.2���� Data transfer option
������� A.3���� Signalling coding mapping
Appendix I � Subscription parameters
������� I.1���� Subscription parameters per interface
������� I.2���� Subscription parameters per PVC