What is the Win9 RTM version?

What is the Win9 RTM version:

Is it necessary for a period of time to press, pack, and sell before the retail store is put on the shelves? So the program code must be completed in a period of time before the official release, the complete program code called Final.code, for example, WINDOWS.XP development, foreign media with Windows XP.goes.Cold to call. After the program code is developed, the master piece is sent to the factory for a large number of presses, and this version is called the RTM version.

The RTM version of the code must be the same as the official version. But the official version also has a different place: for example, the official version of the OEM can not upgrade the installation, upgrade to a new installation will check the old version of the operating system CD-ROM and so on, these are RTM and the official version of the difference, but their main program code are the same. Strictly speaking, this version belongs to the FPP Retail edition and needs to be activated.