X / Open was a consortium of manufacturers and users of Unix systems with the aim of developing Unix to an open system, ie to unify the available for Unix application software, and to provide for these common interfaces. Thus, the dependence of the Unix users of systems and computers certain vendors should be avoided, improving the interoperability of applications and porting software to be facilitated. In 1996, the X / Open consortium merged with the Open Software Foundation for Open Group.


Founded in 1984, the consortium Its founding members were the European companies Bull, ICL, Siemens, Olivetti, and Nixdorf.; This group called itself at the time after formed from the initials of the company Apronym BISON. After later Philips and Ericsson had joined the consortium, the group took the name of X / Open.

The consortium published its specifications under the name X / Open Portability Guide ( XPG ). The first edition of the specifications ( XPG1 ) 1984 touched on basic interfaces of the Unix operating system. XPG2 of 1987 dealt with the internationalization, inter-process communication, and the programming languages ​​C, Cobol, Fortran, Pascal, declarative query language SQL and the data access method ISAM. XPG3 followed anno 1988; its primary goal was to bring about a convergence with the POSIX operating system specification.

By 1990 the number of members rose to 21; the other companies in addition to the first seven, all European companies were AT & T, Digital, Unisys, Hewlett -Packard, IBM, NCR, Sun Microsystems, Prime Computer, Apollo Computer from North America; Fujitsu, Hitachi, NEC of Japan; further the Open Software Foundation and Unix International.

X / Open held from 1993 to 1996 the rights to the brand name UNIX ® holds; After merging with the Open Software Foundation 's rights were transferred to the successor organization to the Open Group.