modular architecture that stressed improved support for enterprise- and network-level administration, drivers for both Token Ring and Ethernet, and a greater ability to run on low-end machine configurations. Multiprocessing became the focus of the final USL-based OEM release of System V, which was Release 4.2MP, released in December 1993. USL continued the publication of an early Unix standard, the System V Interface Definition (SVID). Moreover, the SVID became one of the bases for the more important, vendor-independent POSIX standard for Unix, which System V Release 4 releases also conformed to, as well as the later Single UNIX Specification. USL produced many books documenting various aspects of Unix System V. USL also provided some training and consulting services for Unix systems. Chorus and Ouverture In 1991, USL forged an arrangement with the French company Chorus Systèmes SA to engage in cooperative work on the Chorus microkernel technology, with the idea of supporting SVR4 on a microkernel and thereby making it more scalable and better suited for parallel and distributed applications. As part of this, USL took a $1 million stake in Chorus Systèmes. Much of the USL Chorus work was done at the USL Europe facility in London. By 1993 the work was still ongoing, with questions of industry standardization of interfaces arising. Unisys was also part of the collaboration effort. Announcements made during 1993 promised an OEM release in 1994 and a general availability release in 1995. This was part of the larger Ouverture project, a $14 million effort that was itself part of the European Strategic Program on Research in Information Technology (ESPRIT), overseen by the European Commission. Other software work Another unit within USL, called the Open Solutions Software business unit and headed by Joel A. Appelbaum, was responsible for other system software that in some way worked in conjunction with Unix. The Tuxedo transaction processing middleware had also been transferred from elsewhere in AT&T to USL. It had originated as the Loop Maintenance Operations System (LMOS) followed by the Unix Transaction System (UNITS) and was used for projects internally within AT&T. It was then renamed by USL and, as Release 4.0 of what was now called Tuxedo, in 1989 was offered for the first time as a commercial product. USL also developed and marketed the OSI Communications Platform, which was an implementation of the OSI protocols for Unix-based networking. C++ language work There was also a languages