European airspace utilizes Reduced Vertical Separation Minimum (RVSM) so instead of a 2000 foot separation (as in the US) you get a 1000 ft separation between FL290 and 410. The flip side to that is unlike the US were you can fly NRP or directs (off airway in class two navigation) in Europe everything has to be on an airway, there are little to no directs and the airspace is very tightly regulated through Eurocontrol and the Central Flow Management Unit (CFMU). There is a document called the Route Availability Document (RAD) that very effectively micromanages the airspace (e.g. out of ZRH
via SPY you can take UM982 to cost out at ERAKA but if you want to cost out at GOMUP UM982 is restricted).
[Edited 2004-03-09 07:30:47]
Please oh please Mr Moderator Nazi, dont delete my thread.