This part of IEC 60793 establishes uniform requirements for measuring the cut-off wavelength of single-mode optical fibre, thereby assisting in the inspection of fibres and cables for commercial purposes. This standard gives methods for measuring the cut-off wavelength for uncabled or cabled single mode telecom fibre. These procedures apply to all category B and C fibre types (see Normative references). There are three methods of deployment for measuring the cut-off wavelength. " Method A: Cable cut-off using uncabled fibre 22 m long sample, »cc " Method B: Cable cut-off using cabled fibre 22 m long sample, »cc " Method C: Fibre cut-off using uncabled fibre 2 m long sample, »c All methods require a reference measurement. There are two reference-scan techniques, either or both of which may be used with all methods: " bend-reference technique. " multimode-reference technique using category A1 multimode fibre.