This record specifies a quadrilateral in space for which the average of the unknown values will be calculated. The values are placed in a record post_quadrilateral_dof with the same index. Internally in TOCHNOG, post_point records are used to evaluate the unknowns on the quadrilateral. In 2D only x_0 y_0 and x_1 y_1 should be specified. The coordinates are defined in the initial mesh. See also: post_quadrilateral_n.