CONTENTS

 2     Location of the loops
 3     Names, types and definitions of the loops
        3.1     Loop a – Digital multiplexer aggregate loop
        3.2     Loop b – Analogue aggregate modem loop
        3.3     Loop c – Analogue line loop
        3.4     Loop d – Digital aggregate modem loop
        3.5     Loop f – Tributary analogue loop
        3.6     Loop g – Tributary digital loop towards the Muldex
        3.7     Loop h – Tributary digital loop towards the tributary interface unit
 4     Use of the loops
 5     Methods of control
 6     Control signalling
        6.1     Alternative A
        6.2     Alternative B
        6.3     Maintenance channel signalling
 7     Routing of the maintenance control signals
 8     Application
 9     Use of the maintenance channel