From LinuxMCE wiki
LinuxMCE maintains 3 simultaneous versions of the software, which we call repositories:
Development: This is what all the developers use. Any new software first goes into the Development repository. This repository may not always be stable.
Testing: Once the developers have decided their code is stable and ready for testing, it gets moved into the next release of the testing repository. This is the repository all the beta testers use. Only bug fixes go into the testing repository. This repository should be considered quite stable.
Release: This is the retail repository that LinuxMCE offers its licensees. It is considered completely tested and stable. The mainstream market uses this repository, although it may not have the latest features or devices since each version must go through a lengthy test process before it is ready for release.
Each numbered version includes all the software. Every software module is updated simultaneously to keep things simple -- there are not separate versions for each module. So, for example, if LinuxMCE releases version 126.96.36.199, then all software modules, whether they have changed or not, will be included in that release. You can check the version/change log on each software module's home page to see what changes, if any, where made to that module in each version.
You can tell what repository a given version comes from based on the number of digits. All versions in the development repository have 4 digits, those in the testing repository have 3 digits, and the versions in the release repository have 2.
The 4 number version consists of the following: [Series].[Major Revision].[Minor Revision].[Build]
The fourth digit -- the Build -- in the development versions is incremented each time a development version is released. When a version is considered stable and ready for testing, a testing release consisting of the first 3 digits is 'frozen'. The minor revision is incremented and all future development goes into the next minor revision. Only patches will be issued for the testing version. If a testing version is considered ready for release, a release version consisting of the first 2 digits, Series.Major revision, is released. Normally a release version will not be changed after the fact. However, if necessary a service pack may be offered for a released version.