You won't see any diagram in the FCOM for the Convergence Function as far as I know; There is only one graph for the Enhanced Loc Capture Function ( see below). In our fleet, all the Airbuses, had the Convergence Function feature but the oldest models did not have the Enhanced Loc Capture Function ( A321-100). You could see clearly the difference during the LOC*.
One of the old A 321-100 was famous for banking suddenly up to 33 degrees while doing a tight localizer interception.
