  The dispersive approach to QCD, which extends the applicability range of
perturbation theory towards the infrared domain, is developed. This approach
properly accounts for the intrinsically nonperturbative constraints, which
originate in the low-energy kinematic restrictions on pertinent strong
interaction processes. The dispersive approach proves to be capable of
describing OPAL (update 2012) and ALEPH (update 2014) experimental data on
inclusive tau lepton hadronic decay in vector and axial-vector channels in a
self-consistent way.
