Minecraft wiki entry for Version_formats, associated text: During Indev, the version number remained at 0.31 for many versions. Midway through the development of Indev, Notch changed the version number from "0.31" to just "Minecraft Indev" ("Indev" is a portmanteau of "in development"). When Infdev started, the version was just changed to "Minecraft Infdev" ("Infdev" is a portmanteau of "infinite development", as Notch added infinite world generation).