typedef SAF_Eval SAF_EvalConstants;
 #define SAF_SPACE_CONSTANT      saf_find_evaluation_constant()      /* identifies an evaluation method that is constant. This
                                                                      * is really just an alias for piecewise constant in which
                                                                      * there is only one piece. */
 #define SAF_SPACE_PWCONST       saf_find_evaluation_piecewise_constant() /* identifies an evaluation method that is piecewise
                                                                      * constant. That is it is constant over each piece in the
                                                                      * EVAL_COLL argument of saf_declare_field(). */
 #define SAF_SPACE_PWLINEAR      saf_find_evaluation_piecewise_linear() /* identifies an evaluation method that is piecewise linear. */
 #define SAF_SPACE_UNIFORM       saf_find_evaluation_uniform()       /* identifies an evaluation method that is a single piece
                                                                      * of linear evaluation such as is common for /uniform/
                                                                      * coordinate fields. */