In 1968 Sendov and Korovkin independently introduced the T-Modulus as
a new measure for the smoothness of functions which already has found
various applications in approximation theory and numerical analysis. H
ere it is employed to derive sharp error bounds for the approximate so
lution of linear two-point boundary value problems for ordinary differ
ential equations. These indeed improve corresponding estimates in term
s of ordinary (L(infinity) -) moduli of continuity. Finally, the effec
t is also discussed in the light of a quantitative resonance theorem.