Minecraft wiki entry for Version_formats, associated text: During pre-Classic, versions were not numbered, and instead labeled with the initials of the game followed by the day of month, hour, and minute the version was released. For example, rd-160052 was released on May 16 at 00:52 (12:52 am Sweden time). The temporary name RubyDung (rd) was used in these versions; RubyDung was a game Notch previously worked on.