ETCS specifications have become part of, or are referred to, the Technical Specifications for Interoperability (TSI) for (railway) control-command systems.
So it is a piece of European legislation managed by the European Union Agency for Railways (ERA).
Annex A describes the technical specifications on interoperability for high-speed (HS) and conventional rail (CR) transport.
Using SRS 2.3.0 a number of railway operators started to deploy ETCS on a large scale, for example the Italian Sistema Controllo Marcia Treno (SCMT) is based on Level 1 balises.
This is a bundle of documents, which may have different versioning for each document. The European railway network grew from separate national networks with little more in common than standard gauge.
Notable differences include voltages, loading gauge, couplings, signalling and control systems.
In its advanced form, all lineside information is passed to the driver wireless inside the cab, removing the need for lineside signals watched by the driver.Further development concentrated on compatibility specification with the earlier Class B systems leading to specifications like Euro ZUB that continued to use the national rail management on top of Eurobalises for a transitional period.Following the experience in railway operation the European Union Agency for Railways (ERA) published a revised specification Class 1 SRS 2.3.0d ("debugged") that was accepted by the European Commission in April 2008.This will give the foundation for a later to be defined automatic train operation.The need for a system like ETCS stems from more and longer running trains resulting from economic integration of the European Union (EU) and the liberalisation of national railway markets.