  We consider the Fredholm one-dimensional boundary-value problems in Sobolev
spaces.We have obtained several important results about the indixes of
functional operators, the criterion of their correct well-posedness, the
criterion of the continuous dependence of the solutions of these problems on
the parameter, the degree of convergence of these solutions, and sufficient
constructive conditions under which the solutions of the most general class of
multipoint boundary-value problems are continuous with respect to the
parameter. Eeach of these boundary-value problems corresponds to a certain
rectangular numerical characteristic matrix with kernel and cokernel of the
same dimension as the kernel and cokernel of the boundary-value problem. The
conditions for the sequence of characteristic matrices to converge are found.
