anchor.diff:        {D0, T0};
       false ->
         case D0 of
  -	true ->
  -	  eval(E1, I, E, K, D, W, T0);
  -	false ->
  -	  eval(E2, I, E, K, D, W, T0)
  +	      true ->
  +	        eval(E1, I, E, K, D, W, T0);
  +	      false ->
  +	        eval(E2, I, E, K, D, W, T0)
         end
     end;
   
  
positive.code:       {D0, T0};
      false ->
        case lists:member(D0, D) of
  	true ->
  	  {lookup_ordinate(D0, K), T0};
  	false ->
  	  {[D0], T0}
        end
    end;
  
  
negative.code:   case D0 of
      {calc, W} ->
        case lists:keyfind(Xi, 1, E) of
  	      {_, E0} ->
  	        {D1, T1} = eval(E0, I, E, K, D, W, T0),
  	        tcache:add(Xi, K, D, W, T1, D1);
  	      false ->
  	        {error, undefined_id, Xi}
        end;
      {calc, _W1} ->
        eval2(Xi, I, E, K, D, W, T0 + 1);
  