Windows 7 worked on Windows 7. These were broadly divided into "core operating system" and "Windows client experience", in turn organized into 25 teams of around 40 developers on average. In October 2008, it was announced that Windows 7 would also be the official name of the operating system. There has been some confusion over naming the product Windows 7, while versioning it as 6.1 to indicate its similar build to Vista and increase compatibility with applications that only check major version numbers, similar to Windows 2000 and Windows XP both having 5.x version numbers. The first external release to select Microsoft
Windows Vista out the entirety of the Windows operating system, and to proactively work towards a development process that would enforce high levels of code quality, reduce interdependencies between components, and in general, "not make things worse with Vista". Since Microsoft decided that Longhorn needed to be further componentized, work started on the Omega-13 series builds where they would componentize existing Windows Server 2003 source code, and over time add back functionality as development progressed. Future Longhorn builds would start from Windows Server 2003 Service Pack 1 and continue from there. This change, announced internally to Microsoft employees on August 26, 2004,