Allthough JAR has one central question bank, each member state is no obliged to use the newest version, and each member state has different approach.
The matter is worsened by the fact that memberstates implement different versions of the ATPL syllabus, and thereby different versions of the central question bank
Examples:
Denmark uses the 1999 revision of the syllabus and uses basically the JAR central question bank
Sweden has implemented the 2008 revision of the syllabus, and has its own reduced question bank of approx 2000 questions taken from the central question bank.
Germany uses the newest 2008/2009 revision.
The revision / question bank version is reflected differently in the various online question bank systems (bristol/aviationexam.com/jaaqb.com etc)