ITU-T REC. H221 - FRAME STRUCTURE FOR A 64 kbit/s CHANNEL IN AUDIOVISUAL TELESERVICES
Introduction
1 Basic principle
2 Frame alignment
    2.1 General
    2.2 Multiframe structure
    2.3 Loss and recovery of frame alignment
    2.4 Loss and recovery of multiframe alignment
    2.5 Procedure to recover octet timing from frame alignment
    2.6 Description of the CRC4 procedure
3 Bit-rate allocation signal (BAS) and switching between configurations
4 Application channel (AC)
5 Access to non-audio information within bits 1-7
ANNEX A Attribute 000 used for BAS encoding
ANNEX B Attribute 001 used for BAS encoding
ANNEX C Attribute 100 used for BAS encoding
ANNEX D Attribute 010 used for BAS encoding
ANNEX E Attribute 011 used for BAS encoding
APPENDIX I Examples for the use of the application channel
    I.1 Binary information
    I.2 Synchronous message-type channel
    I.3 Asynchronous message-type channel
    I.4 Error correction and encryption
Reference