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Rishi is correct in his answer, however if you want to keep your discs in "top order" then have a look at the answer I provided at http://questions.x-plane.com/3121/there-way-not-have-unlock-xplane-every-time-start-the-program
I have one and it works perfectly and my discs are stored away hopefully never to be pulled out again.
Hope this helps.
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