From the 'Auction details' page expanded [Lots] view you can click the 'Lot Number' and go to the specific 'Lot Details' page.

Note : By clicking the [Edit] icon to the right of the 'Lot Number', you can go direct to the 'Lot edit' page where you can change the catalogue text.

Or you can access lots by navigating to the 'Lots' search via the administration menu.

From the 'Lot Details' page you can click [Edit] to change the lot catalogue text.

On completing your changes push [Save] to commit your changes, [Delete] to delete the lot or [Cancel] to abandon the changes.