anchor.diff:                          Key=imem_sql_expr:bind_tree(KeyBind,Recs), 
                           Fx = fun(X) -> 
                               OldVal = Proj(X),
  -                            case imem_datatype:io_to_db(Item,OldVal,term,undefined,undefined,<<>>,false,Value) of
  -                                OldVal ->   X;
  -                                NewVal ->   ?replace(X,Cx,maps:put(Key,NewVal,?BoundVal(B,X)))
  +                            case {Value, OldVal} of 
  +                                {?navio,?nav} ->
  +                                    X;                % attribute still not present
  +                                {?navio,_} ->
  +                                    ?replace(X,Cx,maps:remove(Key,?BoundVal(B,X)));
  +                                _ ->
  +                                    case imem_datatype:io_to_db(Item,OldVal,term,undefined,undefined,<<>>,false,Value) of
  +                                        OldVal ->   X;
  +                                        NewVal ->   ?replace(X,Cx,maps:put(Key,NewVal,?BoundVal(B,X)))
  +                                    end
                               end
                           end,     
                           {Cx,0,Fx};
  
positive.code:                         end,     
                          {Cx,Pos,Fx};
                      {map_get,KeyBind,#bind{tind=?MainIdx,cind=Cx}} ->
                          Key=KeyBind,    % imem_sql_expr:bind_tree(KeyBind,Recs), 
                          Fx = fun(X) -> 
                              NewVal = imem_datatype:io_to_db(Item,<<>>,term,undefined,undefined,<<>>,false,Value),
                              ?ins_repl(X,Cx,maps:put(Key,NewVal,#{}))
  
negative.code:     NewRec = if_call_mfa(IsSec, apply_validators, [SKey, DefRec, element(?MainIdx, UpdatedRecs), Tab]),
      Action = [{S,Tab,Typ}, Item, element(?MainIdx,Recs), NewRec, Trigger, User, TrOpts],     
      update_prepare(IsSec, SKey, TableInfo, ColMap, CList, [Action|Acc]);
  update_prepare(IsSec, SKey, {S,Tab,Typ,DefRec,Trigger,User,TrOpts}=TableInfo, ColMap, [[Item,ins,Recs|Values]|CList], Acc) ->
      % ?Info("ColMap~n~p~n", [ColMap]),
      % ?Info("Values~n~p~n", [Values]),
      if  
  