  Within the differential equation method for multiloop calculations, we
examine the systems irreducible to $\epsilon$-form. We argue that for many
cases of such systems it is possible to obtain nontrivial quadratic constraints
on the coefficients of $\epsilon$-expansion of their homogeneous solutions.
These constraints are the direct consequence of the existence of symmetric
$(\epsilon+1/2)$-form of the homogeneous differential system, i.e., the form
where the matrix in the right-hand side is symmetric and its
$\epsilon$-dependence is localized in the overall factor $(\epsilon+1/2)$. The
existence of such a form can be constructively checked by available methods and
seems to be common to many irreducible systems, which we demonstrate on several
examples. The obtained constraints provide a nontrivial insight on the
structure of general solution in the case of the systems irreducible to
$\epsilon$-form. For the systems reducible to $\epsilon$-form we also observe
the existence of symmetric form and derive the corresponding quadratic
constraints.
