RULE ... TO table.column

Saluton,

I am using

,----
|  SELECT version();
|                 version
| --------------------------------------------------------------------
|  PostgreSQL 7.0.2 on i586-pc-linux-gnulibc1, compiled by gcc 2.95.1
| (1 row)
`----

, and upgrading to 7.1 is not possible (it was hard enough to get the
admin to upgrade from 6.5.3).

While the docs say that I can create a rule on table.column, I get the
error message:

,----
| litdb=> create rule no_update_on_journal_title__rl as
| litdb->   on update to journal.title do instead nothing;
| ERROR:  attribute level rules currently not supported
`----

Am I doing something wrong here, or do I have to work around this via
... where old.title = new.title ... (would this work?), or should I
use a before-trigger?

Are ``attribute level rules'' supported in 7.1 (so I can at least put
a note into the code)?

Thanks in advance,

Albert.