--- capa/capa51/pProj/capaCommon.c	2000/01/25 17:14:29	1.4
+++ capa/capa51/pProj/capaCommon.c	2000/01/31 18:34:13	1.5
@@ -3079,7 +3079,7 @@ capa_check_answer(p, answer) Problem_t *
                 }
                 given = n_part * scale; /* convert the given answer into proper scale for units */
                 sig = calc_sig( input );
-                if( (sig < sig_l) || (sig > sig_u) ) {
+                if( ((sig < sig_l) || (sig > sig_u)) && (sig!=0)) {
                   result = SIG_FAIL;
                 } else {
                   switch( tol_type ) {
@@ -3151,6 +3151,10 @@ capa_check_answer(p, answer) Problem_t *
           result = check_formula_ans(correct,answer,p->id_list,p->pts_list,tol_type,tol);
           break;
     case ANSWER_IS_EXTERNAL: /* not yet implemented */
+         /* we assume the external program is called through popen() */
+         /* and the result will be given back as 0 or 1 to indicate the */
+         /* given answer is correct or not */
+         
           break;
     
   }