GEGN8601 Iss 1

This Guidance Note is intended for transport operators, project entities, assessment bodies and other organisations with responsibilities related to the application of National Technical Specification Notices (NTSNs). It provides guidance on the NTSNs' regulatory context, roles and responsibilities, transition regimes, conformity assessments and related processes.

NTSNs came into effect in Great Britain (GB) on 1 January 2021. They replaced and substantially reproduced the content of the Technical Specifications for Interoperability, which apply in the European Union. Seven revised NTSNs were published on 2 May 2025.

This Guidance Note provides general information on topics that are relevant to multiple NTSNs. It covers the regulatory context, roles and responsibilities, the links between NTSNs and other parts of the framework, implementation and conformity assessment. The focus is on application, including assessments and transition regimes between different versions of requirements. The guidance is relevant to both sets of NTSNs published in January 2021 and May 2025.

This Guidance Note combines, updates and fills gaps in existing guidance, to put relevant industry agreed information in a single place.

General guidance for National Technical Specification Notices