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• CCITT Recommendation R.115 (11/1988) – MAINTENANCE LOOPS FOR TDM-SYSTEMS
• 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