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• CCITT Rec. M.251 (11/1988) – MAINTENANCE FUNCTIONS TO BE IMPLEMENTED IN CCITT-MML
• 1 Introduction
• 2 System functions
• 3 Scope
• 4 Maintenance functions in the various maintenance phases
  • 4.1 Failure detection
  • 4.2 System protection (under study)
  • 4.3 Failure information (under study; e.g. change of alarm levels)
  • 4.4 Failure location
  • 4.5 Failure correction (under study)
  • 4.6 Verification
  • 4.7 Restoration
• 5 Other maintenance functions
• 6 Relation to Recommendation Z.331 "Maintenance functions"
• 7 Description of maintenance functions in annexes to this Recommendation
• ANNEX A – General description of maintenance tests/measurements
• A.1 Introduction
• A.2 Tests and measurements
• ANNEX B – General description of failure information
• ANNEX C – Protection, restoration
• ANNEX D – Support of maintenance
• References