  We consider the UV divergences up to sub-sub leading order for the four-point
on-shell scattering amplitudes in D=8 supersymmetric Yang-Mills theory in the
planar limit. We trace how the leading, subleading, etc divergences appear in
all orders of perturbation theory. The structure of these divergences is
typical for any local quantum field theory independently on renormalizability.
We show how the generalized RG equations allow one to evaluate the leading,
subleading, etc. contributions in all orders of PT starting from one-, two-,
etc. loop diagrams respectively. We focus then on subtraction scheme dependence
of the results and show that in full analogy with renormalizable theories the
scheme dependence can be absorbed into the redefinition of the couplings. The
only difference is that the role of the couplings play dimensionless
combinations like g^2s^2 or g^2t^2, where s and t are the Mandelstam variables.
