CTP Expiration Dates

Is there a document that lists the expiration dates of the CTP releases? We've a test box still on CTP15 and I was wondering when the CTP will stop working.
There is no paper that lists them all but I think in 15's case it will be soon, its almost a year since it was released.|||The agreed licence statement in the setup tells you that the CTP will loose it licence when the version is pubslihed, so you should either consider to remove or upgrade your current system.

HTH, Jens Suessmeyer.

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