How do you know if Win8 is the official version?

After the release of Windows8, it seems that many versions are circulating on the Internet, but which one is the official version?
There is no install.wim in the system image file from the genuine iso (228 oceans) that I got from Microsoft websetup. Instead, install.esd, so you just need to mount the iso file to check if there is an install.esd file under the source under the root directory. If there is an official version, there is no official version.
The simpler way is that the official version of the image will not exceed 2.75GB, even if it is 64-bit, it is 2.75GB, so those above 3GB will be the previous version of ……
In addition: MSDN and RTM In terms of function, it is the same as the official version of win8. It can also be activated (purchased) with the official version of the key. The students who have already installed it do not need to reinstall it, and now the official version of iso is not really good. ……