ERA Railway Terminology visual v0 featured

ERA Railway Terminology Collection

Last updated: 12 March 2026

The ERA Railway Terminology Collection gathers terms and abbreviations that are contained in the EU legal framework for railway, technical documents produced by bodies which are engaged in the development of important evolution in the railway system and other relevant glossaries.

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Starting with "O" (248)

Disclaimer
ERA Railway Terminology Collection is a consultation tool, developed to support the sharing of information through the actors involved in running the Single European Railway Area (SERA). The responsibility for the correctness, completeness, accuracy, or reliability of the information in ERA RTC lays upon the authors of the definitions, as they derive from reference documents having their own preparation and approval flow. Users cannot call ERA liable for the use they make of the content. Please consider that when the collection is exported (.csv) and then printed or converted, it becomes uncontrolled.
Term	Context	Document Type	Origin document
On-Board recording device	ERTMS	Technical Document	ERTMS/ETCS - Glossary of Terms and Abbreviations - version : 4.0.0 - date 05/07/2023
On-board signalling	Interoperability	Decision	Commission Decision of 30 November 2009 on the reference document referred to in Article 27(4) of Directive 2008/57/EC of the European Parliament and of the Council on the interoperability of the rail system within the Community. (2009/965/EC)
On-board systems	Safety / SSC-SA	Directive	Directive (EU) 2016/798 of the European Parliament and of the Council of 11 May 2016 on railway safety (recast)
On-board tools and portable equipment	Interoperability	Decision	Commission Decision of 30 November 2009 on the reference document referred to in Article 27(4) of Directive 2008/57/EC of the European Parliament and of the Council on the interoperability of the rail system within the Community. (2009/965/EC)
On-Board Unit	ERTMS	Technical Document	ERTMS/ETCS - Glossary of Terms and Abbreviations - version : 4.0.0 - date 05/07/2023
On-ground energy data collecting system (data collecting service) (DCS)	Energy	TSI	Commission Regulation (EU) No 1301/2014 of 18 November 2014 on the technical specifications for interoperability relating to the energy subsystem of the rail system in the Union
On-Line KMS	ERTMS	Technical Document	ERTMS/ETCS - Glossary of Terms and Abbreviations - version : 4.0.0 - date 05/07/2023
On-premises ICT infrastructure	Telematics Applications for Passenger and Freight Services	Regulation	Regulation (EU) 2023/2854 of the European Parliament and of the Council of 13 December 2023 on harmonised rules on fair access to and use of data and amending Regulation (EU) 2017/2394 and Directive (EU) 2020/1828	Latest release
ONC	International Standard	EU Technical Document	CEN CENELEC ABBRAVIATION ACRONYM 2025
One stop shop	Withdrawn	TSI	Commission Regulation (EU) No 454/2011 of 5 May 2011 on the technical specification for interoperability relating to the subsystem ‘telematics applications for passenger services’ of the trans-European rail system	Latest release
One Stop Shop (OSS)	Withdrawn	TSI	Commission Regulation (EU) No 1305/2014 of 11 December 2014 on the technical specification for interoperability relating to the telematics applications for freight subsystem of the rail system in the European Union and repealing the Regulation (EC) No 62/2006	Latest release
One way journey	Withdrawn	Application Guide	TAP TSI Annex B.54 Indirect Fulfilment application_guide - version 1.0 of 06/12/2013	Latest release
One-phase signal	International Standard	ISO	ISO/IEC 10026-1:1998(en) Information technology — Open Systems Interconnection — Distributed Transaction Processing — Part 1: OSI TP Model
One-stop shop	Vehicles / VA	Application Guide	Guidelines for the practical arrangements for the vehicle authorisation process - v. 2.1 on 14/02/2024
One-Stop Shop (OSS)	RNE Glossary	Glossary	RNE Glossary - NS_CID_Glossary_2025
ONH	International Standard	EU Technical Document	CEN CENELEC ABBRAVIATION ACRONYM 2025
Online interface	Single Market Mutual Recognition Conformity Assessment	Regulation	Regulation (EU) 2023/988 of the European Parliament and of the Council of 10 May 2023 on general product safety, amending Regulation (EU) No 1025/2012 of the European Parliament and of the Council and Directive (EU) 2020/1828 of the European Parliament and the Council, and repealing Directive 2001/95/EC of the European Parliament and of the Council and Council Directive 87/357/EEC
Online marketplace	Security	Directive	Directive (EU) 2022/2555 of the European Parliament and of the Council of 14 December 2022 on measures for a high common level of cybersecurity across the Union, amending Regulation (EU) No 910/2014 and Directive (EU) 2018/1972, and repealing Directive (EU) 2016/1148 (NIS 2 Directive)
Online search engine	Security	Directive	Directive (EU) 2022/2555 of the European Parliament and of the Council of 14 December 2022 on measures for a high common level of cybersecurity across the Union, amending Regulation (EU) No 910/2014 and Directive (EU) 2018/1972, and repealing Directive (EU) 2016/1148 (NIS 2 Directive)
ONP	EU Policy	EU Technical Document	Technical document from the Publications Office of the European Union - ‘Style guide’ Coordination Interinstitutional Style Guide - version on 19.04.2022

Common Safety Method
Conformity Assessment
Control-Command and Signalling
Data Protection
Energy
Entity in Charge of Maintenance
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International Relations
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Safety / SSC-SA
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SERA_EU Transport
Single Market Mutual Recognition Conformity Assessment
SMS Safety Culture Human and Organisational Factor
Telematics Applications for Passenger and Freight Services
Vehicles / VA
Withdrawn

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