Just for a bit of further info you've also got the NATO sizes which work in the same way as the above but relate to a size range rather than a specific size. I've got a S95 jacket here which is a 180/104. So far so good. It's NATO size is 7080/9505, though, which looks baffling until you look closer. The first part is the height range (1)70cm to (1)80cm tall, the second the chest size 95cm to (1)05cm. The hundred (1) is always omitted to make it a standard 8 digit number. Any questions?
The point of all this is that you can then get to grips with sizing stuff from other NATO countries which otherwise can be a bit of a struggle.
Cheers, David