> Just to assure me....
>
> In a trigger that is defined as BEFORE UPDATE can I use
>
> OLD.SomeValue<>NEW.SomeValue

Yes, just be aware that this expression will return NULL
if one of values is NULL. I.e.

IF (OLD.SomeValue<>NEW.SomeValue)
THEN ... values are different ...
ELSE ... values are equal OR one or both values are NULL

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