CONTENTS

 1     Introduction
        1.1     Scope
        1.2     References
        1.3     Abbreviations
 2     Frame structures
        2.1     Frame structure at 34 368 kbit/s
                  2.1.1     General
                  2.1.2     Overhead allocation
        2.2     Frame structure at 44 736 kbit/s
                  2.2.1     Intermediate 500 ms frame structure
                  2.2.2     Overhead allocation
        2.3     Frame structure at 97 728 kbit/s
                  2.3.1     General
                  2.3.2     Overhead allocation
        2.4     Frame structure at 139 264 kbit/s
                  2.4.1     General
                  2.4.2     Overhead allocation
 3     Multiplexing structures
        3.1     Support of SDH elements in the 34 368 kbit/s frame structure
                  3.1.1     Coding of multiframe indicator for Tributary Unit multiframe indication
        3.2     Support of SDH elements in the 44 736 kbit/s frame structure
        3.3     Support of SDH elements in the 97 728 kbit/s frame structure
        3.4     Support of SDH elements in the 139 264 kbit/s frame structure
                  3.4.1     Multiplexing of 20 ´ TUG-2
                  3.4.2     Multiplexing of 2 ´ TUG-3 and 5 ´ TUG-2
                  3.4.3     Coding of multiframe indicator for Tributary Unit multiframe indication
Annex A – Description of the 16-byte frame and CRC-7 calculation