  Radiative effects in semi-inclusive hadron leptoproduction of unpolarized
particles are calculated within the leading order approximation. The
contributions of the infrared-free sum of the effects of real and virtual
photon emission as well as the contribution of exclusive radiative tail are
considered. It is demonstrated how the obtained formulae in the leading log
approximation can be obtained using the standard approach of the leading log
approximation as well as from the exact expressions for the radiative
correction of the lowest order. The method of the electron structure function
is used to calculate the higher order corrections. The results are analytically
compared to the results obtained by other groups. Numeric illustrations are
given in the kinematics of the modern experiments at Jefferson Laboratory.
