  An automorphism group of an incidence structure I induces a tactical
decomposition on I. It is well known that tactical decompositions of t-designs
satisfy certain necessary conditions which can be expressed as equations in
terms of the coefficients of tactical decomposition matrices. In this article
we present results obtained for tactical decompositions of q-analogs of
t-designs, more precisely, of 2-(v,k,lambda_2;q) designs. We show that
coefficients of tactical decomposition matrices of a design over finite field
satisfy an equation system analog to the one known for block designs.
Furthermore, taking into consideration specific properties of designs over the
binary field, we obtain an additional system of inequations for these
coefficients in that case.
