What does ABS class notation AMS mean?

AMS is a classification notation that, together with the Maltese Cross + symbol, indicates that a vessel's machinery, boilers and systems have been constructed and installed under survey by the American Bureau of Shipping (ABS) in accordance with the requirements of the ABS Rules. The + AMS notation is intended for all new construction of ABS classed self-propelled vessels and offshore units.

The AMS notation, without the Maltese Cross + symbol, is assigned to self-propelled vessels and offshore units for which the machinery, boilers and systems have not been constructed and installed under survey by the Bureau, but are found satisfactory with regard to ABS requirements.