# Commission Decision of 7 November 2006 concerning a technical specification for interoperability relating to the control-command and signalling subsystem of the trans-European high speed rail system and modifying Annex A to Decision 2006/679/EC concerning the technical specification for interoperability relating to the control-command and signalling subsystem of the trans-European conventional rail system (notified under document number C(2006) 5211) (Text with EEA relevance) (2006/860/EC), Division 7.2.9: Rolling stock with train protection Class A and Class B equipment

Extent: E+W+S+N.I.

Rolling stock may be equipped with both Class A and Class B systems to enable operations on several lines. The Class B systems may be implemented
using an STM that may be plugged into the ERTMS equipment (‘external STM’), or
integrated within the ERTMS/ETCS equipment.
Also, the Class B system could be implemented independently (or, in case of upgrade or renewal, be left ‘ as is ’ ), in case of Class B systems for which an STM is not an economically viable alternative, from the rolling stock owner’s point of view. However, if a STM is not used, the Railway Undertaking must ensure that the absence of a ‘ handshake ’ (= handling, by ETCS, of transitions between Class A and Class B on track-side) nevertheless is properly managed.
When running on a line which is equipped with both Class A and Class B systems, the Class B systems may act as fallback arrangement for the Class A system if the train is equipped with both Class A and Class B systems. This cannot be a requirement for interoperability and is not valid for GSM-R.

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Source: https://www.legislation.gov.uk/eudn/2006/860/annex/division/7/division/7.2/division/7.2.9 (the official version)
Page: https://openlegislation.uk/eu-decision-2006-860/annex/division-7/division-7.2/division-7.2.9
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.