Halfdan, the front 2-8 row or so are blocked out for Europe Select, depending on how many people purchase those tix.
It's worth mentioning here that on F100s and 737s, the front X rows have much better seat pitch than the rest of the aircraft, with the exception of exits.
If you book the first row or two of economy you usually get excellent legroom compared to the rest of the afct (I'm > 6ft).
I used to always book exit rows because of the extra legroom but gave up because four different times I booked what was listed as an exit on the seat map (both online checkin and KLM pdf seat maps) and got a row in front of or behind the exit row! It seems not all the planes are numbered the same, at least the F70s and F100s.
Back in Feb I gave up and booked seats at the front of economy and was very suprised to find out that there's 36-in or so of legroom.
I've had great luck since then booking right at the front of econ.
Check out other threads on this forum for info about which seats NOT to sit in, for example I believe Row 8 or 9 on 737s doesn't have a window.