> I did search with google and in IBPhoenix site, but didn't find
> a clear definition for the "read only transaction". Also I remember
> reading something like "readonly transaction is started in
> read committed mode and therefore does not stop OIT
> advancing .." but can't find this link any more :(

"read only" and "read committed" are two independent properties
of transaction (i.e. "read only" does not imply "read committed" mode).
However, if you do not want to stop OIT advancing,
you have to use both.

Ivan Prenosil
http://www.volny.cz/iprenosil/interbase