It's a bug???? 8-()

Hello, deary ALL ! What your say about this :
I-have-a-simple-table :

create table task_l(
n serial,
event text,
URL text, /* ссылка */
PID int, /* PID wget-а для данной
задачи*/
descripition text, /*описание*/
start_time datetime DEFAULT (now()), /* время запуска*/
end_time datetime, /*время останова*/
status text /*результат выполнения :
OK,ERROR,ABORTED */
);
/* AND RULE */
create rule r_3 as
on UPDATE to task_l.url do
update task_l set start_time=now();

AND..... ERROR!!!!:

psql:3.sql:3: ERROR: attribute level rules currently not supported

But is the another solution for that's task : "write in EACH record
date-time last change!(or last select acces)"

Ok. Its not a error - its a feature ( IMHO very stupid ;-\ )
create rule r_3 as
on UPDATE to task_l.url do
^^^^^^^ I remove this and get forever-loop when
user update start_time.
Yes I make field start_time in client read-only, but..... its
solution only for one case !!!!
Does any-body tell me best solution???

with regards Vic.