Multi-user, 32-bit OS, mainly for business. Many add-on features available: multi-user DOS/Windows and TCP/IP support for setting up web servers. Since its start in the late 1970s as OASIS, it has steadily improved and added options while keeping its user friendly status.

Makes access control, revenue control, and security management software. THEOS-based, integrated with Windows 3.x/95/98-NT/XP, has Web interface.

Custom THEOS Programming

Growing article, with links to many related topics. Wikipedia.