  New superconvergent structures are introduced by the finite volume element
method (FVEM), which allow us to choose the superconvergent points freely. The
general orthogonal condition and the modified M-decomposition (MMD) technique
are established to prove the superconvergence properties of the new structures.
In addition, the relationships between the orthogonal condition and the
convergence properties for the FVE schemes are carried out in Table 1.
Numerical results are given to illustrate the theoretical results.
