This technical report is a supplement to IEC 61156-1 Edition 3 (2007): Multicore and symmetrical pair/quad cables for digital communications – Part 1: Generic specification. This technical report covers the following topics following this standard: – the near-end crosstalk test methods and length correction procedures of 6.3.5; – the far-end crosstalk test methods and length correction procedures of 6.3.6; – the concatenation of measured cable segments, even if they are of different design. The final objective of this technical report is to describe the mathematics involved to model the concatenation of cable sections of different length, not based upon measurements but based upon the specification limits of the cables involved. This is required as a base foundation of the complete channel modelling, involving also the connectivity covered by IEC SC48B towards channels, as required and requested by ISO/IEC JTC1/SC25 WG3 for incorporation into ISO/IEC 11801:2002 [1] 1. This TR is informative and contains observations and recommendations applicable to using the length correction formulas for either measurements or modelling of balanced cables.