Each platform update is named with a YYMM pattern, for example the update for September in the year 2014 is represented with 1409. For incremental and bugfix releases, we’re using a decimal notation, eg. 1409.1.
Each month a new major version is released, however a previous version is always kept until the next major release.
Projects using the latest platform version will be automatically upgraded to the new release. In the case where a project is using the previous major version, its platform will be upgraded to a version which was considered current in that month. Simply put, when a new update is rolled out, the project’s platform version is bumped up by one.
To see the changes for each platform version, visit the platform changelog.