1. Scope
2. Normative references
   2.1 Identical Recommendations / International
       Standards
   2.2 Paired Recommendations / International
       Standards equivalent in technical content
   2.3 Additional references
3. General considerations
   3.1 Compatibility with versions of
       Recommendation X.25
   3.2 Environments
   3.3 Differences in DTE/DTE and DTE/DCE
       operation
   3.4 Operation over circuit-switched connections
   3.5 Provision of the OSI Network Service
   3.6 External Packet Layer interactions
   3.7 Logical channels
   3.8 Packet Layer entity
   3.9 Packet types
   3.10 Procedures for initialization
4. Procedures for restart
   4.1 Originating a restart request
   4.2 Receiving a restart indication
   4.3 Restart collision
   4.4 Restart confirmation
   4.5 Determining "DTE" or "DCE" characteristics
5. Procedures for Virtual Call setup and clearing
   5.1 Ready state
   5.2 Procedures for Virtual Call setup
   5.3 Rejecting a call
   5.4 Aborting a call request
   5.5 Procedures for Virtual Call clearing
6. Procedures for data and interrupt transfer
   6.1 States for data and interrupt transfer
   6.2 Maximum User Data Field length of DATA packets
   6.3 Delivery Confirmation bit
   6.4 More Data mark
   6.5 Complete packet sequence
   6.6 Qualifier bit
   6.7 Fragmentation and reassembly of messages
   8.8 Procedures for interrupt
   6.9 Transit delay of DATA packets
7. Procedures for flow control
   7.1 Flow control
   7.2 Throughput characteristics and throughput
       classes
8. Procedures for reset
   8.1 Originating a reset request
   8.2 Receiving a reset indication
   8.3 Reset collision
   8.4 Reset confirmation
9. Effects of clear, reset, and restart procedures
   on the transfer of packets
10.Effects of Layers 1 and 2 on the Packet Layer
11.Error handling
   11.1 The DIAGNOSTIC packet
   11.2 Nonreceipt of window-rotation information
   11.3 Receipt of erroneous DATA packets
12.Packet formats
   12.1 General
   12.2 Call setup and call clearing packets
   12.3 DATA and interrupt packets
   12.4 Flow control packets
   12.5 Reset packets
   12.6 Restart packets
   12.7 DIAGNOSTIC packet
   12.8 REJECT packet
   12.9 Registration packets
13.Procedures for optional user facilities
   13.1 On-line Facility Registration
   13.2 Extended Packet Sequence Numbering
   13.3 D-bit Modification
   13.4 Packet Retransmission
   13.5 Incoming Calls Barred
   13.6 Outgoing Calls Barred
   13.7 One-way Logical Channel Outgoing
   13.8 One-way Logical Channel Incoming
   13.9 Nonstandard Default Packet Sizes
   13.10 Nonstandard Default Window Sizes
   13.11 Default Throughput Classes Assignment
   13.12 Flow Control Parameter Negotiation
   13.13 Throughput Class Negotiation
   13.14 Closed User Group related facilities
   13.15 Bilateral Closed User Group related
         facilities
   13.16 Fast Select
   13.17 Fast Select Acceptance
   13.18 Reverse Charging
   13.19 Reverse Charging Acceptance
   13.20 Local Charging Prevention
   13.21 Network User Identification (NUI) related
         facilities
   13.22 Charging Information
   13.23 ROA related facilities
   13.24 Hunt Group
   13.25 Call Redirection and Call Deflection related
         facilities
   13.26 Called Line Address Modified Notification
   13.27 Transit Delay Selection and Indication
   13.28 Alternative Addressing related facilities
   13.29 Reference Number
14.Procedures for optional ITU-T specified DTE
   facilities
   14.1 Calling Address Extension
   14.2 Called Address Extension
   14.3 Minimum Throughput Class Negotiation
   14.4 End-to-End Transit Delay Negotiation
   14.5 Priority
   14.6 Protection
   14.7 Expedited Data Negotiation
15.Format for Facility Field in call setup/clearing
   packets
   15.1 General
   15.2 Coding of the Facility Field for optional user
        facilities
   15.3 Coding of the Facility Field for ITU-T
        specified DTE facilities
16.Format for Registration Field registration packets
   16.1 General
   16.2 Coding of the Registration Field for
        registration facilities
17.Diagnostic codes
18.Timers and retransmission counts
19.State diagrams
20.State tables
21.Conformance
   21.1 Static conformance
   21.2 Protocol Implementation Conformance Statement
   21.3 Dynamic conformance
Annexes
A Private networks
B PICS Proforms
C Differences between various editions of ISO/IEC 8208
D Abbreviations