Internal version numbers（转自Wikipedia中Version条目）

Software may have an "internal" version number which differs from the version number shown in the product name (and which typically follows version numbering rules more consistently). J2SE 5.0, for example, has the internal version number of 1.5.0, and versions of Windows from 95 on have continued the standard numerical versions internally: Windows 95 is Windows 4.0, 98 is 4.10, 2000 is 5.0, XP is 5.1, 2003 is 5.2, and Vista is 6.0.