ERA Railway Terminology visual v0 featured

ERA Railway Terminology Collection

Last updated: 5 December 2025.

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" (211)

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
OAPEC	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
OAS	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
OAU	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
OBB	ERTMS	Glossary	ERTMS Glossary
Object colour	International Standard	ISO	ISO 3864-4:2011(en) Graphical symbols — Safety colours and safety signs — Part 4: Colorimetric and photometric properties of safety sign materials
Objective	Common Safety Method	Application Guide	Safety management system requirements for safety certification or safety authorisation. Version 1.3 Manuscript completed in April 2021
Objective evidence	International Standard	ISO	ISO 19011:2018(en) Guidelines for auditing management systems	Latest release
Objectivity	EU Policy	Regulation	Regulation (EC) No 223/2009 of the European Parliament and of the Council of 11 March 2009 on European statistics and repealing Regulation (EC, Euratom) No 1101/2008 of the European Parliament and of the Council on the transmission of data subject to statistical confidentiality to the Statistical Office of the European Communities, Council Regulation (EC) No 322/97 on Community Statistics, and Council Decision 89/382/EEC, Euratom establishing a Committee on the Statistical Programmes of the European Communities
Observation	RNE Glossary	Glossary	RNE Glossary - NS_CID_Glossary_2025
Observer	International Standard	ISO	ISO/IEC 17021-1:2015(en) Conformity assessment — Requirements for bodies providing audit and certification of management systems — Part 1: Requirements	Latest release
Observer	International Standard	ISO	ISO 19011:2018(en) Guidelines for auditing management systems	Latest release
Obstacle-free route	Persons with Reduced Mobility	TSI	Commission Regulation (EU) No 1300/2014 of 18 November 2014 on the technical specifications for interoperability relating to accessibility of the Union's rail system for persons with disabilities and persons with reduced mobility.
OBU	ERTMS	Technical Document	ERTMS/ETCS - Glossary of Terms and Abbreviations - version : 4.0.0 - date 05/07/2023
OBU	Control-Command and Signalling	ERA Technical Document	Guideline - Certification: Restrictions and added functions V1.0 of 18.06.2024
OBU	RNE Glossary	Glossary	RNE Glossary - NS_CID_Glossary_2025	Latest release
OBU	ERTMS	Glossary	ERTMS Glossary
OC	Infrastructure	Application Guide	Guide on the application of the common specifications of the register of Infrastructure - v. 3.1.0 on 31.03.2025	Latest release
OCAS	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
OCC	ERTMS	Glossary	ERTMS/ATO Glossary - version 2 on 05.07.2023
OCC	Freight	Glossary	Transport of dangerous goods. Risks Management Framework. Framework glossary v. 1.0/2018

Common Safety Method
Conformity Assessment
Control-Command and Signalling
Data Protection
Energy
Entity in Charge of Maintenance
ERTMS
EU Policy
Freight
Human and Organisational Factor
Infrastructure
International Relations
International Standard
Interoperability
Noise
Operation
Persons with Reduced Mobility
Railway Tunnels
Registers
Regulation
RNE Glossary
Safety / SSC-SA
Security
SERA_EU Transport
Single Market Mutual Recognition Conformity Assessment
Telematics Applications for Freight
Telematics Applications for Passenger
Vehicles / VA
Withdrawn

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ERA Technical Document
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