This Recommendation defines end-to-end error performance parameters and objectives for international digital paths which operate at or above the primary rate and for international digital connections which operate below the primary rate of the digital hierarchy. The objectives given are independent of the physical network supporting the path or connection. For digital paths which operate at or above the primary rate, this Recommendation is based upon a block-based measurement concept using error detection codes inherent to the path under test. This supports in-service measurements. For digital connections which operate below the primary rate of the digital hierarchy, this Recommendation is based upon bit error and bit error ratio measurements. This approach does not support in-service measurements. Annex A deals with the definition of availability of the path or connection. Annexes B, C and D give specific information concerning PDH, SDH and cell-based transmission paths. It is not required to apply this Recommendation to connections which operate below the primary rate using equipment designed prior to the adoption of this Recommendation in December 2002. This Recommendation deals with the performance of PDH paths, and of those SDH paths using equipment designed prior to the adoption of ITU-T Rec. G.828 in March 2000. ITU-T Rec. G.828 deals with the performance of SDH paths using equipment designed as of or after the adoption of ITU-T Rec. G.828 in March 2000. New Recommendation G.8201 deals with performance of ODUk paths of the OTN.