Examples of B were found in open source, including some versions of the OpenJDK.

Mac OS was said to skip 9 on the way to 10 due to a combo of some Asian numerology (just as Western numerology often encourages skipping "unlucky" 13) and also trying to make a clean break more obvious between System 8 and OSX. (The X being the 10, as Apple's favorite way to write 10 for various reasons. Which is why "OSX" was always a misnomer, accidentally burning the version number into the operating system name. Part of why Apple has been trying to get everyone on the "macOS" brand lately to pull the version number back out.)