I think that is the "drop", i.e. drop 7 in the case of your jacket, which, is a pretty typical drop- in inches or cm. If the jacket is a 44(in), the waist on the pants would be @ 37"...should work the same in centimeters/Euro sizing (54-7= 47cm, x2/2.54= appx 37"). It generally applies to suits, and that jacket looks like it is probably a suit orphan. You will will see a drop listed on true sport coats as well- I have heard that it can refer to the waist measurement of the jacket in that case, but not really sure if that is totally correct.
Thanks a lot; I wasn't aware of that. :)