Connecting the world and beyond

Short history of Study Group 17

ITU-T Study Group 17 (SG17) was formed by the merger of ITU-T Study Groups 7 and 10 in 2001.

Study Group 7 had its roots back to the Joint Working Party on New Data Networks, which was created by the IVth Plenary Assembly of the CCITT (Consultative Committee for International Telephony and Telegraphy) in 1968. Table 1 below shows the evolution over the various study periods and the study group leadership until the merger with Study Group 10 in 2001. Its work programme evolved significantly over this time. In the late 60s and early 70s, its work focused on digital leased lines and digital circuit switched data networks with the first X-series Recommendations approved at the December 1972 Vth CCITT Plenary Assembly. Packet switched networks was the hot topic of the 70s and 80s with the first edition of the famous X.25 Recommendation approved in 1976. An ever-increasing number of packet data network Recommendations were developed and approved in 1980, 1984 and 1988. Work on Open Systems Interconnection (OSI) in conjunction with ISO and IEC began in the early 80s and was very intense through the 80s and 90s. By 2000, this work had reached maturity and SG7 began to build its efforts on security.

Study Group 10 had its roots as part of the work of CCITT Study Group XI with three Questions (out of eleven Questions) on languages for stored program control telephone exchanges adopted by the Vth CCITT Plenary Assembly in 1972. Table 2 below shows the evolution over the various study periods and the study group leadership until the merger with SG7 in 2001. In 1976, skeleton Recommendations on Specification and Description Language (SDL) and Man-Machine Language (MML) were adopted as the first Z-series Recommendations. These were further developed in the next 8 years along with CHILL with approvals in 1980 and 1984. The VIIIth CCITT Plenary Assembly in October 1984 established Study Group 10. By 2000, a suite of Z-series Recommendations was in place with MSC (Message Sequence Chart) as the major addition in the 1990s. Focus in the later years moved to aligning ITU-T languages, such as SDL and MSC, to OMG’s UML (Unified Modeling Language).

In 2001, TSAG agreed to merge Study Groups 7 and 10 to form Study Group 17 (7 + 10 = 17). The chairs of the two Study Groups became co-chairs of the new Study Group 17 and all the vice chairs of the two study groups became vice-chairs of the new Study Group 17. Table 3 below shows the evolution of Study Group 17 over seven study periods and the study group leadership. A major change was made at WTSA-04 when the remaining work on data networks was transferred to ITU-T Study Group 13 and the major focus of Study Group 17 was shifted to security while also continuing its work on languages. By WTSA-08, a substantial set of security Recommendations had been approved and WTSA-08 changed the title of Study Group 17 to Security. The role of Study Group 17 was essentially continued by WTSA-12 and strengthened by WTSA-16, WTSA-20 and WTSA-24.

Study Group 17 currently has lead study group responsibilities for:

Table 4 shows the history of X and Z series Recommendations approved by the various CCITT Plenary Assemblies. After 1988, Recommendations were developed, approved and published individually, rather than in the sequence of color books published every four years. The X-series expanded in scope over the years from “New data networks” to “Data communication networks” to “Data networks and open system communications” to “Data networks, open system communications and security”. In a similar manner, the Z-series expanded over the years from “Programming languages for SPC exchanges" to "Programming languages”, to “Languages and general software aspects for telecommunication systems”. Tables 5, 6, 7, 8 and 9 show the set of 503 approved Recommendations and 42 approved Supplements under the responsibility of Study Group 17 as of 1 December 2025, among which over 250 standards (ITU-T Recommendations) focus on security.

Table 1 - Leadership of Study Group 7 and predecessors

Study Period	Designation	Name	Chair	Vice-chairs	Number of Questions
1969-1972	JWP/NRD	New data networks	O. A. OHLMER (Germany)	V. C. MACDONALD (Canada)	1
1973-1976	Study Group VII	New networks for data transmission	V. C. MACDONALD (Canada)	N. R. CRANE (Australia) H. GABLER (Germany) A. E. SERRURE (Belgium)	1 (25 points)
1977-1980	Study Group VII	New networks for data transmission	V. C. MACDONALD (Canada)	J. CHAPMAN (UK) N. R. CRANE (Australia) M. KATO (Japan) A. TEXIER (France)	34
1981-1984	Study Group VII	Data communication networks	V. C. MACDONALD (Canada)	H. V. BERTINE (USA) M. KATO (Japan) L. Lavandera SANCHEZ (Spain) A. TEXIER (France) J. O. WEDLAKE (UK)	41
1985-1988	Study Group VII	Data communication networks	J. O. WEDLAKE (UK)	H. V. BERTINE (USA) P. G. BOWIE (Canada) P. GUINAUDEAU (France) L. Lavandera SANCHEZ (Spain) R. PARODI (Italy) S. TOMITA (Japan)	48
1989-1992	Study Group VII	Data communications networks	J. O. WEDLAKE (UK)	H. V. BERTINE (USA) P. G. BOWIE (Canada) L. Lavandera SANCHEZ (Spain) J. PARK (Australia) R. PARODI (Italy) P. PUGES (France) S. TOMITA (Japan)	15
1993-1996	Study Group 7	Data networks and open systems communications	H. V. BERTINE (USA)	V. OSSIPOV (Russia) S. TOMITA (Japan) C. H. YIM (Korea)	25
1997-2000	Study Group 7	Data networks and open system communications	H. V. BERTINE (USA)	Y. H. LEE (Korea) Y. HIRAMATSU (Japan) V. OSSIPOV (Russia)	25
2001-16/9/01	Study Group 7	Data networks and open systems communications	H. V. BERTINE (USA)	B.-M. CHIN (Korea) V. OSSIPOV (Russia)	14

Table 2 - Leadership of Study Group 10 and predecessors

Study Period	Designation	Name	Chair	Vice-chairs	Number of Questions
1973-1976	Study Group XI	Telephone switching and signalling	J. S. RYAN (USA)	T. MOUSSA (Cameroon) P. PLEHIERS (Belgium) P. STERNDORFF(Denmark)	3 out of 11
1977-1980	Study Group XI	Telephone switching and signalling	J. S. RYAN (USA)	C. A. ADEOYE (Nigeria) P. PLEHIERS (Belgium) P. STERNDORFF(Denmark)	3 out of 13
1981-1984	Study Group XI	Telephone switching and signalling	J. S. RYAN (USA)	P. COLLET (France) S. KANO (Japan) P. PLEHIERS (Belgium)P. STERNDORFF(Denmark)	3 out of 19
1985-1988	Study Group X	Languages and methods for telecommunications applications	C. CARRELLI (Italy)	K. KATZEFF (Sweden) N. A. MARTELLOTTO (USA) K. SCHULZ (Germany)	9
1989-1992	Study Group X	Languages for telecommunication applications	C. CARRELLI (Italy)	O. F. FAERGEMAND (Denmark) B. LINDBERG (S) K. SCHULZ (Germany)	12
1993-1996	Study Group 10	Languages for telecommunication applications	O. F. FAERGEMAND (Denmark)	K. SCHULZ (Germany)	10
1997-2000	Study Group 10	Languages and general software aspects for telecommunication systems	A. SARMA (Germany)	A. MEISINGSET (Norway)	13
2001-16/9/2001	Study Group 10	Languages and general software aspects for telecommunication systems	A. SARMA (Germany)	V. EFIMOUCHKINE (Russia) A. MEISINGSET (Norway) O. MONKEWICH (Canada)	13

Table 3 - Leadership of Study Group 17

Study Period	Designation	Name	Chair(s)	Vice-chairs	Number of Questions
17/9/2001-2004	Study Group 17	Data networks and telecommunication software	Co-chairs: Herbert BERTINE (USA) and Amardeo SARMA (Germany)	Byoung-Moon CHIN (Korea) Vladimir EFIMOUCHKINE (Russia) Arve MEISINGSET (Norway) Ostap MONKEWICH (Canada) V. OSSIPOV (Russia)	27
2005-2008	Study Group 17	Security, languages and telecommunication software	Herbert BERTINE (USA)	Jianyong CHEN (China) Byoung-Moon CHIN (Korea) Arkadiy KREMER (Russia) Arve MEISINGSET (Norway) Ostap MONKEWICH (Canada) Yu WATANABE (Japan)	17
2009-2012	Study Group 17	Security	Arkadiy KREMER (Russia)	Jianyong CHEN (China) Mohamed M.K. ELHAJ (Sudan) Antonio GUIMARAES (Brazil) Patrick MWESIGWA (Uganda) Koji NAKAO (Japan) Heung Youl YOUM (Korea)	15
2013-2016	Study Group 17	Security	Arkadiy KREMER (Russia)	Khalid BELHOUL (UAE) Mohamed M.K. ELHAJ (Sudan) Mario German Fromow RANGEL (Mexico) Antonio GUIMARAES (Brazil) Zhaoji LIN (China) Patrick MWESIGWA (Uganda) Koji NAKAO (Japan) Sacid SARIKAYA (Turkey) Heung Youl YOUM (Korea)	12
2017-2021	Study Group 17	Security	Heung Youl YOUM (Korea)	Vasiliy DOLMATOV (Russia) Gökhan EVREN (Turkey) Inette FUREY (USA)^Note1 Juan GONZALEZ (USA)^Note1Muataz Elsadig ISHAG (Sudan) Patrick-Kennedy KETTIN ZANGA (Central African Republic)^Note3 Eric Anicet MBATHAS (Central African Republic)^Note3 Wala LATROUS (Tunisia) Zhaoji LIN (China) Hugo Darío MIGUEL (Argentina)^Note2 ^{Francisco Javier DIAZ(Argentina)^Note2} Yutaka MIYAKE (Japan)	12
2022-2024	Study Group 17	Security	Heung Youl YOUM (Korea)	Samir ABDELGAWAD (Egypt) Laial ALMANSOURY (Kuwait) Afnam ALROMI (Saudi Arabia) Abderrazak BACHIR BOUIADJRA (Algeria)^Note5 Abdenour BOURENNANE (Algeria)^Note5Gökhan EVREN (Turkey) Yutaka MIYAKE (Japan) Francisco Javier DIAZ(Argentina)^Note4 Lia MOLINARI (Argentina)^Note4 Kwadwo OSAFO-MAAFO (Ghana) Greg RATTA (USA)^Note6 Pushpendra Kumar SINGH (India) Arnaud TADDEI (United Kingdom) Wala TURKI LATROUS (Tunisia) Liang WEI (China)	12
2025-2028	Study Group 17	Security	Arnaud TADDEI (United Kingdom)	Laial ALMANSOURY (Kuwait) Afnam ALROMI (Saudi Arabia) Farhad BELONOGOV (Uzbekistan) Abdenour BOURENNANE (Algeria)^Note7 Fatah DOUMAZ (Algeria)^Note7Samir GABER ABD EL GAWAD (Egypt) Takamasa ISOHARA (Japan) Honey MAKOLA (South Africa) Kwadwo OSAFO-MAAFO (Ghana)^Note8 Prince ANKRAH (Ghana)^Note8 Michael ROSA (United States) Preetika SINGH (India) Liang WEI (China) Mahmut Esat YILDIRM (Turkiye)

Note1 Inette FUREY (USA) replaced by Juan GONZALEZ (USA), March 2018
Note2 Hugo Darío MIGUEL (Argentina) replaced by Francisco Javier DIAZ (Argentina), March 2020

Note3 Patrick-Kennedy KETTIN ZANGA (Central African Republic) replaced by Eric Anicet MBATHAS (Central African Republic), August 2020

Note4 Francisco Javier DIAZ (Argentina) replaced by Lia MOLINARI (Argentina), September 2022

Note5 Abderrazak BACHIR BOUIADJRA (Algeria) replace by Abdenour BOURENNANE (Algeria), February 2023

Note6 Greg RATTA (USA) resigned 8 September 2023 (retirement)

Note7 Abdenour BOURENNANE (Algeria) replaced by Fatah DOUMAZ (Algeria), May 2025
Note8 Kwadwo OSAFO-MAAFO (Ghana) replaced by Prince ANKRAH (Ghana), April 2026

Table 4 - CCITT Plenary Assemblies and Recommendations Approved

Study Period	Book	Plenary Assembly	Dates	X-series Recommendations	Z-series Recommendations
1969-1972	Green Book	Vth CCITT Plenary Assembly	4-15 December 1972	11 (Public data networks - X.1, X.2, X.20, X.21, X.30, X.31, X.32, X.33, X.40, X.50, X.70)
1973-1976	Orange Book	VIth CCITT Plenary Assembly	27 September – 8 October 1976	24 (Public data networks)	3 (SDL – Z.100-series) 8 (MML – Z.300-series)
1977-1980	Yellow Book	VIIth CCITT Plenary Assembly	10-21 November 1980	39 (Public data networks)	4 (SDL – Z.100-series) 1 (CHILL – Z.200) 9 (MML – Z.300-series)
1981-1984	Red Book	VIIIth CCITT Plenary Assembly	8-19 October 1984	56 (Public data networks) 9 (OSI – X.200-series) 8 (MHS – X.400-series)	5 (SDL – Z.100-series) 1 (CHILL – Z.200) 15 (MML – Z.300-series)
1985-1988	Blue Book	IXth CCITT Plenary Assembly	14-25 November 1988	72 (Public data networks) 23 (OSI – X.200-series) 9 (MHS – X.400-series) 8 (Directory – X.500-series)	1 (SDL – Z.100) 1 (FDTs – Z.110) 1 (CHILL – Z.200)

Table 5 - D-series Recommendations under the responsibility of Study Group 17*/a>

TARIFF AND ACCOUNTING PRINCIPALS AND INTERNATIONAL
TELECOMMUNICATION/ICT ECONOMIC AND POLICY ISSUES

Subject	Recommendation Series	Number of Texts
Recommendations for international telecommunication/ICT economic and policy issues	D.1000-D.1199	1
Economic and policy aspects of big data and digital identity in international telecommunications services and networks	D.1140-D.1159	1
*In conjunction with Study Group 3

Table 6 - E-series Recommendations under the responsibility of Study Group 17*

OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS

Subject	Recommendation Series	Number of Texts
International operation	E.100-E.229	2
General provisions concerning Administrations	E.104-E.119	2
Network management	E.400-E.489	1
International network management	E.405-E.419	1
* These 3 Recommendations are in conjunction with Study Group 2

Table 7 - F-series Recommendations under the responsibility of Study Group 17

NON-TELEPHONE TELECOMMUNICATIONS SERVICES

Subject	Recommendation Series	Number of Texts
Message handling services	F.400-F.499	11
Directory services	F.500-F.549	4

Table 8 - X-series Recommendations under the responsibility of Study Group 17

DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY

Subject	Recommendation Series	Number of Texts
Open Systems Interconnection	X.200-X.299	48
Model and notation	X.200-X.209	2
Service definitions	X.210-X.219	11
Connection-mode protocol specifications	X.220-X.229	10
Connectionless-mode protocol specifications	X.230-X.239	6
PICS proformas	X.240-X.259	8
Protocol Identification	X.260-X.269	3
Security Protocols	X.270-X.279	2
Layer Managed Objects	X.280-X.289	5
Conformance testing	X.290-X.299	1
Message Handling Systems	X.400-X.499	25
Directory	X.500-X.599	13
OSI networking and system aspects	X.600-X.699	42 + 1 Supp.
Networking	X.600-X.629	7
Efficiency	X.630-X.639	6
Quality of service	X.640-X.649	2
Naming, Addressing and Registration	X.650-X.679	15 + 1 Supp.
Abstract Syntax Notation One (ASN.1)	X.680-X.699	12
Security	X.800-X.849	20 + 5 Supp.
OSI applications	X.850-X.899	14
Commitment, Concurrency and Recovery	X.850-X.859	3
Transaction processing	X.860-X.879	4
Remote operations	X.880-X.889	3
Generic applications of ASN.1	X.890-X.899	4
Open distributed processing	X.900-X.999	13
Information and network security	X.1000-X.1099	48 + 7 Supp.
Security orchestration and service access	X.1000-X.1011	2
Network security	X.1030-X.1049	17 + 1 Supp.
Security management	X.1050-X.1069	11+ 6 Supp.
Telebiometrics	X.1080-X.1099	18
Secure applications and services (1)	X.1100-X.1199	44 + 9 Supp.
Multicast security	X.1100-X.1109	1
Home network security	X.1110-X.1119	4 + 1 Supp.
Mobile security	X.1120-X.1139	7 + 2 Supp.
Web security (1)	X.1140-X.1149	9 + 4 Supp.
Application security (1)	X.1150-X.1159	10 + 2 Supp.
Peer-to-peer security	X.1160-X.1164	4
Data protection (1) and networked ID security	X.1165-X.1179	1
IPTV security	X.1180-X.1199	8
Cyberspace security	X.1200-X.1299	55 + 18 Supp.
Cybersecurity	X.1200-X.1229	16 + 5 Supp.
Countering spam	X.1230-X.1249	17 + 9 Supp.
Identity management (IdM) and Authentication	X.1250-X.1299	22 + 4 Supp.
Secure applications and services (2)	X.1300-X.1499	61
Emergency communications	X.1300-X.1309	2
Ubiquitous sensor network security	X.1310-X.1319	4
Smart grid security	X.1330-X.1339	3
Certified mail	X.1340-X.1349	1
Internet of things (IoT) security	X.1350-X.1369	13
Intelligent transportation system (ITS) security	X.1370-X.1399	14
Distributed ledger technology (DLT) security	X.1400-X.1429	15
Application Security (2)	X.1450-X.1459	7
Web security (2)	X.1470-X.1489	2
Cybersecurity information exchange	X.1500-X.1599	21
Overview of cybersecurity	X.1500-X.1519	2
Vulnerability/state exchange	X.1520-X.1539	10
Event/incident/heuristics exchange	X.1540-X.1549	4
Exchange of policies	X.1550-X.1559	1
Identification and discovery	X.1570-X.1579	1
Assured exchange	X.1580-X.1589	3
Cloud computing security	X.1600-X.1699	17
Overview of cloud computing security	X.1600-X.1601	2
Cloud Computing security requirements, security capabilities	X.1602-X.1629	6
Cloud Computing security best practices and guidelines	X.1640-X.1659	9
Quantum communication	X.1700-X.1729	8
Quantum random number generator	X.1702-X.1704	1
Quantum Key Distribution Network (QKDN)	X.1705-X.1749	7
Data security	X.1750-X.1799	5
Big Data Security	X.1750-X.1759	3
Data protection (II)	X.1770-X.1799	2
International Mobile Telecommunications (IMT) security	X.1800-X.1839	10 + 1 Supp.
IMT-2020 security	X.1810-X.1839	10 + 1 Supp.
Metaverse and digital twin security	X.2000-X.2199	4
Digital twins	X.2000-X.2049	3
Smart community	X.2050-X.2099	1
Other metaverse security	X.2100-X.2149	0
Software supply chain security	X.2150-X.2199	0
Artificial Intelligence (AI) / Machine Learning (ML) security	X.2200-X.2249	0
Decentralized / Digital Identity	X.2300-X.2349	0

Table 9 - Z-series Recommendations under the responsibility of Study Group 17

LANGUAGES AND GENERAL SOFTWARE ASPECTS FOR TELECOMMUNICATION SYSTEMS

Subject	Recommendation Series	Number of Texts
Formal description techniques (FDT)	Z.100-Z.199	35 + 1 Supp.
Specification and Description Language (SDL)	Z.100-Z.109	9 + 1 Supp.
Application of formal description techniques	Z.110-Z.119	3
Message Sequence Chart (MSC)	Z.120-Z.129	2
User Requirements Notation (URN)	Z.150-Z.159	2
Testing and Test Control Notation (TTCN)	Z.160-Z.179	19
Programming languages	Z.200-Z.299	1
CHILL: The ITU-T high level language	Z.200-Z.209	1
Quality	Z.400-Z.499	1
Quality of telecommunication software	Z.400-Z.409	0
Quality aspects of protocol-related Recommendations	Z.450-Z.459	1
Middleware	Z.600-Z.699	0
Processing environment architectures	Z.600-Z.609	0