With the Airbus A319, what do the additional things mean??

Question

for instance, what is the difference between the A319-131 and the A319-111?

Thank you

Answer 1

the 131, and 111 are usually sub model numbers.  Maybe more seating capacity, or a major design change and such.

Answer 2

Each airline has a "code" at the end, eg 131 and 111.

The first one, means which series of A319 the aircraft is...

1 - A319-100 series

And the 11 means, the 1996 engines varient - CFM56-5B5 or 5B5/P

The 131 means the 1997 engines varient - IAE Model V2522-A5