Amendment 1 to Recommendation ITU-T G.650.1 (2010) is aimed to provide measurement procedures for coherent multi-path interference (MPI) in a short optical fibre cables (jumpers). An improvement in bending-loss in a single-mode fibre affects not only the fundamental mode but may also influence the higher order modes. This may change the cut-off wavelength mechanism. In this case, the single-mode operability of an optical fibre can be investigated by evaluating the MPI characteristics.