anchor.diff:      case Dm:retract_clause(Dr0, Functor, Ct) of
   	{ok,Dr1} -> Db#db{ref=Dr1};
   	error ->
  -	    permission_error(modify, static_procedure, pred_ind(Functor), Db)
  +	    permission_error(modify, static_procedure, pred_ind(Functor))
       end.
   
   %% abolish_clauses(Functor, Database) -> NewDatabase.
  
positive.code:     case Dm:assertz_clause(Dr0, Functor, Head, Body) of
  	{ok,Dr1} -> Db#db{ref=Dr1};
  	error ->
  	    permission_error(modify, static_procedure, pred_ind(Functor), Db)
      end.
  
  well_formed_clause(Head, Body, Db) ->
      try
  	{functor(Head),well_form_body(Body, false, sture)}
      catch
  	throw:{erlog_error,E} -> erlog_error(E, Db)
      end.
  
  %% retract_clause(Functor, ClauseTag, Database) -> NewDatabase.
  %%  Retract (remove) the clause with tag ClauseTag from the list of
  
negative.code:     case Dm:asserta_clause(Dr0, Functor, Head, Body) of
  	{ok,Dr1} -> Db#db{ref=Dr1};
  	error ->
  	    permission_error(modify, static_procedure, pred_ind(Functor))
      end.
  
  assertz_clause({':-',H,B}, Db) -> assertz_clause(H, B, Db);
  