Ah, I got that wrong. Yes, Windows XP was the rebranded Windows NT 5. Thank you for the correction.

AFAIK, Windows was discontinued after Vista. Windows 7 is actually the 7^th iteration of the Microsoft version of OS/2, which was rebranded as Windows NT with the release of the third version, and as Windows sine NT with the seventh version. Windows 9 had to be skipped because a sloppy version check for Windows 95/98 would have failed.