ISO/IEC and The Open Group announce international approval of the joint revision to POSIX and the Single UNIX Specification

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ISO/IEC Joint Technical Committee has approved the joint revision to POSIX and the Single UNIX Specification as an International Standard. Designated as ISO/IEC 9945:2002, the joint revision forms the core of The Open Group's Single UNIX Specification Version 3 (IEEE 1003.1-2001, POSIX.1).

The standard reflects a collaborative effort of industry and formal standardization within the Austin Group, currently chaired by The Open Group's Director of Certification, Andrew Josey. The initiative has included a wide spectrum of participants from industry, academia, government, and the open source community.

"The Open Group congratulates the members of the Austin Group for reaching

this land-mark integration of formal and industry standards," said Allen Brown, President and CEO of The Open Group. "We are proud to work with the IEEE and ISO/IEC in facilitating the merger of these significant specifications, and adoption by ISO/IEC recognizes the importance of them to the industry globally."

According to John Hill, Chair of ISO/IEC/JTC 1 SC 22 which approved the new standard, ISO/IEC 9945: 2002, Information technology – Portable Operating System Interface (POSIX), represents a milestone of cooperation between ISO/IEC JTC 1, Information technology, and The Open Group. "The collaborative efforts of these two organizations have proven to be exemplary. JTC 1's experts in POSIX have been working hard to bring together the POSIX standards, with The Open Group's Single Unix Specification, to unify the market place."

The quality and coherence of the standard, together with broad-based support, make it a representative example of the success that comes from standardizing open systems specifications. I think this project, and the standard that resulted, are models that will show the way for many future joint projects, all to the satisfy user needs."

"The ISO/IEC adoption of the merged IEEE POSIX specifications and the UNIX specification recognizes the significant benefits to the industry and to end users of the work of the Austin Group. Their diligent efforts in harmonizing the formal standards processes with the industry and the open source community provide the assurance of this solid foundation continuing, preserving the high value of investments associated with software systems," stated Judith Gorman, Managing Director of IEEE Standards.

The combining of the IEEE POSIX specifications and the Single UNIX Specification into ISO/IEC 9945:2002 Parts 1 to 4 replaces the existing ISO/IEC 9945-1:1996 (IEEE 1003.1, 1996 version), and ISO/IEC 9945-2:1993 (IEEE Std 1003.2, 1992 version).

ISO/IEC 9945 consists of the following parts, under the general title Information technology Portable Operating System Interface (POSIX):

  • Part 1: Base Definitions
  • Part 2: System Interfaces
  • Part 3: Shell and Utilities
  • Part 4: Rationale

For more information, visit

About the Open Group

The Open Group, a vendor-neutral and technology-neutral consortium, has a vision of Boundaryless Information Flow achieved through global interoperability in a secure, reliable and timely manner. The Open Group's mission is to drive the creation of Boundaryless Information Flow by working with customers to capture, understand and address current and emerging requirements, establish policies, and share best practices; working with suppliers, consortia and standards bodies to develop consensus and facilitate interoperability, to evolve and integrate specifications and open source technologies; offering a comprehensive set of services to enhance the operational efficiency of consortia; and developing and operating the industry's premier certification service and encouraging procurement of certified products. More information on the organization can be found at

About ISO and IEC

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) are non-governmental organizations that form a specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.

About JTC 1

JTC 1, the Joint ISO/IEC technical committee, works to develop, maintain, promote and facilitate information technology standards required by global markets. Established in 1987, JTC 1 is made up of 24 participating countries with an additional 42 countries which participate as observers in the committee's technical work. JTC 1 collaborates with ISO/IEC technical committees and other management level groups as well as industry and consortia. To date, the committee has published over 600 standards.

About The Single UNIX Specification

The Open Group has been the custodian of the specification for the UNIX system and the trademark since 1993. The effort that led to this transfer was the catalyst for all vendors to make their systems conform to this single definition, a goal that had been elusive in previous harmonization efforts. Today all the major vendors support the Single UNIX Specification and have registered product. For information on registered products see

In keeping with The Open Group's policy of open and free access to its standards, the standard is available at

For more information on the UNIX system and the UNIX certification program, see the UNIX system web site at

For more information on version 3 of the Single UNIX Specification, refer to

Note to editors
UNIX is a registered trademark of The Open Group in the US and other countries.


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