Editing Unix System Laboratories (section)

==Unix System V work==
[[Image:USL office in Summit with room number.jpg|thumb|left|Multi-part room numbers were characteristic of the AT&T heritage of the USL office in Summit]]
{{main|UNIX System V}}
One unit within USL, called the UNIX System V Software business unit and headed by Michael J. DeFazio, was responsible for the development of the UNIX System V base technology.<ref name="pr-rosetta"/>  DeFazio had held a similar role within USO.<ref name="pr-uso"/>
The USO/USL staff was heavily involved in the creation of [[SVR4|UNIX System V Release 4]], which shipped in 1989 and was a joint project with [[Sun Microsystems]].<ref name="timeline"/>  This work incorporated technology from a variety of Unix-based efforts, including [[UNIX System V]], [[Berkeley Software Distribution|BSD]], and [[Xenix]].<ref name="timeline">{{cite web | url=http://www.unix.org/what_is_unix/history_timeline.html | title=History and Timeline | publisher=The Open Group | access-date=December 1, 2017 | archive-date=April 8, 2011 | archive-url=https://web.archive.org/web/20110408171534/http://www.unix.org/what_is_unix/history_timeline.html | url-status=live }}</ref>  There were additions and new innovations as well from both the AT&T and Sun sides.   System V Release 4 debuted at the [[Unix Expo]] trade show in New York in November 1989, in the form of source code availability for it as well as demonstrations from Unix International of SVR4-based applications running on seventeen different vendor platforms.<ref>{{cite news | url=https://books.google.com/books?id=dTAEAAAAMBAJ&pg=PA41 | title=Hopes of Reunification Highlight Eventful Year for Unix Community | first=Martin | last=Marshall | newspaper=InfoWorld | date=December 18, 1989 | page=41 | access-date=March 28, 2021 | archive-date=March 28, 2021 | archive-url=https://web.archive.org/web/20210328062559/https://books.google.com/books?id=dTAEAAAAMBAJ&pg=PA41 | url-status=live }}</ref>  End-user versions of Release 4 became available during 1990.<ref name="advanced"/>

Next USL engaged in an especially arduous effort into trying to satisfy the requirements of the [[National Computer Security Center]]'s [[Trusted Computer System Evaluation Criteria]] ("Orange Book") to the B2 level.<ref name="cw-sec">{{cite news | url=https://books.google.com/books?id=a6P8XXI-B8cC&pg=PA32 | title=AT&T Unix to gain enhanced security | first=Johanna | last=Ambrosio | newspaper=Computerworld | date=October 1, 1990 | page=32 | access-date=March 28, 2021 | archive-date=March 28, 2021 | archive-url=https://web.archive.org/web/20210328062612/https://books.google.com/books?id=a6P8XXI-B8cC&pg=PA32 | url-status=live }}</ref>  This manifested itself in System V Release 4.1 ES (Enhanced Security), which also included generally useful features such as support for dynamic loading of kernel modules.<ref>{{cite news |title=Unix International reviews the Unix System V.4 story so far |first=William |last=Fellows |date= August 13, 1992 |work=[[Computergram International]] | publisher=Computer Business Review |url=https://techmonitor.ai/technology/unix_international_reviews_the_unix_system_v4_story_so_far <!--blacklisted http://www.cbronline.com/news/unix_international_reviews_the_unix_system_v4_story_so_far --> }}</ref>

Following that, USL worked on [[UNIX System V#SVR4.2 / UnixWare|System V Release 4.2]], which was released in June 1992.<ref name="iw-42">{{cite news | url=https://books.google.com/books?id=7D0EAAAAMBAJ&pg=PA1 | title=Univel targets UnixWare release for early fall | first1=Vance | last1=McCarthy | first2=Cate | last2=Corcoran | newspaper=InfoWorld | date=May 11, 1992 | pages=1, 103 | access-date=March 28, 2021 | archive-date=March 28, 2021 | archive-url=https://web.archive.org/web/20210328062558/https://books.google.com/books?id=7D0EAAAAMBAJ&pg=PA1 | url-status=live }}</ref>  ''[[InfoWorld]]'' characterized this effort as "at the core of an assault on the enterprise networking market," with a 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.<ref name="iw-42"/>

Multiprocessing became the focus of the final USL-based OEM release of System V, which was Release 4.2MP, released in December 1993.<ref name="timeline"/>

USL continued the publication of an early Unix standard, the [[System V Interface Definition]] (SVID).<ref name="advanced"/>  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]].<ref name="advanced">{{cite book <!-- | https://books.google.com/books?id=_kpsAQAAQBAJ&pg=PA33 --> | title=Advanced Programming in the UNIX Environment | first1=W. Richard | last1=Stevens | first2=Stephen A. | last2=Rago | publisher=Addison-Wesley | edition=Third | location=Upper Saddle River, New Jersey | date=2013 | pages=32–33}}</ref>

USL produced many books documenting various aspects of Unix System V.<ref>{{cite web | url=http://worldcat.org/identities/lccn-n91048302/ | title=Identities: UNIX System Laboratories | publisher=WorldCat | access-date=May 6, 2018 | archive-date=May 7, 2018 | archive-url=https://web.archive.org/web/20180507003515/http://worldcat.org/identities/lccn-n91048302/ | url-status=live }} WorldCat lists "122 works in 297 publications in 1 language and 1,849 library holdings" from USL.</ref>  
USL also provided some training and consulting services for Unix systems.<ref name="pr-finalized"/>