NTP uses A.B.C - style release numbers. At the moment: A is 4, for ntp V4. B is the major release number. C is the minor release number. Even numbers are 'stable' releases and odd numbers are "development" releases. Following the release number may be the letter 'p' followed by a number. This indicates a point (or patch) release. Release candidates have -RC in the release number. Here are some recent versions numbers as an example: 4.2.2 A production release (from the ntp-stable repository) 4.2.2p2 A production release (from the ntp-stable repository) 4.2.3p12 A development release 4.2.3p15-rc1 A release candidate for 4.2.4 Note that after the ntp-dev repo produces a production release it will be copied into the ntp-stable and the cycle will repeat. Feel free to suggest improvements...