  Power corrections in QCD (both conventional and unconventional ones arising
from the ultraviolet region) are discussed within the infrared finite
coupling-dispersive approach. It is shown how power corrections in Minkowskian
quantities can be derived from the corresponding ones in associated Euclidean
quantities through analyticity, allowing a parametrization in term of the
Euclidean coupling and a renormalon-free perturbative expansion. It is argued
that one should in general expect coefficients functions computed in the true
non-perturbative vacuum to differ from the standard perturbative ones, even
without assuming new physics. A phenomenology of $1/Q^2$ terms arising from
eventual new physics of ultraviolet origin is also set-up. Models for
non-perturbative contributions to the (universal) QCD coupling are suggested.
Issues of renormalization scheme dependence are commented upon.
