FL 250 is in the Maastricht Airspace, however is delegated to Amsterdam after/abm BERGI for departures Amsterdam FIR subject to co-ordination with London; in other words being used as a westbound level,
This saves on co-ordination for tfc climbing above the division level as otherwise it would climb to FL240, than a release would have to be obtained from 240 to FL250, as 245 can be used in an emergency, and then a further release above FL250 from Maastricht.
Sounds complicated but it goes back to when Maastricht took over the Dutch UIR and considerable time and effort was spent by some in Amsterdam and Den Haag to make life difficult