Thank you bigmac .
Now, another piece of info about Belgium :
Their Governement decided some years ago that their air force should buy F16s. ( there are around 50 left ) and Alpha jets (also around 50 ) to train they need aispace, and seen the size of Belgium, their training areas when active take roughly half of Belgium, reducing the Luxemburg sector to a mere crossing point of 4 different airways, that you overfly in 4 minutes, during which time you all have to change of FL to avoid the others coming from the 3 other directions...