Described by "InfoWorld" as "an open systems solution with the Macintosh at its heart", the operating system is based on UNIX System V Release 2.2. It includes some additional features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It is POSIX- and System V Interface Definition (SVID)-compliant and includes TCP/IP networking from version 2 onward. Having a Unix-compatible, POSIX-compliant operating system made it possible for Apple to bid for large contracts to supply computers to U.S. federal government institutes.