# The Railways (Interoperability) Regulations 2011, Paragraph 1: List of subsystems


For the purposes of these Regulations, the system constituting the rail system may be broken down into the following subsystems, either—
(a) structural areas—
infrastructure,
energy,
trackside control-command and signalling,
on-board control-command and signalling,
rolling stock.
(b) functional areas—
operation and traffic management,
maintenance,
telematics applications for passenger and freight services.

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Source: https://www.legislation.gov.uk/uksi/2011/3066/schedule/3/paragraph/1 (the official version)
Page: https://openlegislation.uk/railways-interoperability-regulations-2011/schedule-3/paragraph-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.