If the error estimation is active, the order of the used proposal functions for a component must be greater than one, if the derivative of this component of the test function or the solution is used in the functional equation. In the other case, order one is sufficient. Copyrights by Universitaet Karlsruhe 1989-1996. Copyrights by Lutz Grosz 1996. All rights reserved.
More details see vecfem .