International Telecommunication Union   ITU
عربي  |  中文  |  Espa˝ol  |  Franšais  |  Русский
 Advanced Search Advanced Search Site Map Contact us Print Version
Home : ITU-T Home : Study Groups : Study Group 17
Question 15/17 – Open Systems Interconnection (OSI)
(Continuation of Q.3/17)


The work on the base Recommendations for Open Systems Interconnection (OSI) has been completed. This includes work on OSI reference model; upper layer (Application, Presentation and Session) structure, services and protocols; and lower layer (Transport, Network, Data Link and Physical) structure, services and protocols. Also mature is the work on Message Handling; Reliable Transfer; Remote Operations; Commitment, Concurrency and Recovery (CCR); and Transaction Processing.

Systems based on these OSI Recommendations may be implemented over a relatively long period of time. Operational experience with implemented systems based on these Recommendations may lead to the discovery of technical errors or desirable enhancements to these Recommendations. Therefore there is a need for ongoing maintenance of X-series OSI Recommendations.

These Recommendations are:

  1. OSI Architecture – X.200, X.210, X.220, X.630, X.650
  2. Message Handling – F.400, F.401, F.410, F.415, F.420, F.421, F.423, F.435, F.440, F.471, F.472, X.400, X.402, X.404, X.408, X.411, X.412, X.413, X.419, X.420, X.421, X.435, X.440, X.445, X.446, X.460, X.462, X.467, X.481, X.482, X.483, X.484, X.485, X.486, X.487, X.488
  3. Transaction Processing – X.860, X.861, X.862, X.863
  4. Commitment, Concurrency and Recovery (CCR) – X.851, X.852, X.853
  5. Remote Operations – X.219, X.229, X.249, X.880, X.881, X.882
  6. Reliable Transfer – X.218, X.228, X.248
  7. Upper Layers – X.287, X.637, X.638, X.639
  8. Application Layer – X.207, X.217, X.217bis, X.227, X.227bis, X.237, X.237bis, X.247, X.257
  9. Presentation Layer – X.216, X.226, X.236, X.246, X.256
  10. Session Layer – X.215, X.225, X.235, X.245, X.255
  11. Lower Layers – X.260
  12. Transport Layer – X.214, X.224, X.234, X.264, X.274, X.284, X.634
  13. Network Layer – X.213, X.223, X.233, X.263, X.273, X.283, X.610, X.612, X.613, X.614, X.622, X.623, X.625, X.633
  14. Data link Layer – X.212, X.222, X.282
  15. Physical Layer – X.211, X.281
  16. Quality of service – X.641, X.642

NOTE – The following closely related Recommendations are the responsibility of other Questions or study groups.

  • The X.290-X.299 series on Conformance Testing is under the responsibility of Question 14/17.
  • The X.500-X.599 series on the Directory is under the responsibility of Question 11/17.
  • The X.600-X.609 series on Multi-peer Communications is under the responsibility of Study Group 11.
  • The X.660-X.679 series on Registration Authorities is under the responsibility of Question 12/17.
  • The X.680-X.699 series on ASN.1 is under the responsibility of Question 12/17.
  • The X.700-X.799 series of Recommendations on Systems Management is under the responsibility of Study Group 2.
  • The X.800-X.849 series of Recommendations on Security is under the responsibility of Question 2/17.
  • The X.890-X.899 series of Recommendations on Generic Applications of ASN.1 is under the responsibility of Question 12/17.


Study items to be considered include, but are not limited to:

  1. Continue maintenance of OSI architecture and individual layer Recommendations to provide any needed enhancements and to resolve any reported defects; and
  2. Continue maintenance of Message Handling Service and Systems, Reliable Transfer, Remote Operations, CCR, and Transaction Processing to provide any needed enhancements and to resolve any reported defects.

This work is to be carried out in collaboration with the ISO/IEC JTC 1.

Close collaboration and liaison with other study groups and other international groups implementing OSI is highly desirable to ensure the widest applicability of resulting Recommendations.


Tasks include, but are not limited to:

  1. Develop corrections or enhancements to OSI Recommendations, as needed, based on received contributions; and
  2. Maintain the OSI Implementers’ Guide and the MHS Implementers’ Guide.


Recommendations: X.290-X.299 series, X.500-X.599 series, X.600-X.609 series, X.660 X.699 series, X.700-X.799 series, X.800-X.849 series and X.890-X899 series

Questions: ITU-T Qs 2, 11, 12, 14/17, 11/2 and 15/11

Study groups: ITU-T SGs 2, 11 and 13

Standardization bodies: ISO/IEC JTC 1


Top - Feedback - Contact Us -  Copyright ę ITU 2009 All Rights Reserved
Contact for this page : TSB EDH
Updated : 2009-01-28