Appendix 2: GLOSSARY (TERMS AND ABBREVIATIONS)

A lot of significant “terms and abbreviations” used in the ETCS (European Train Control System) domain
(European Directives, FRS and SRS, Operational Rules, etc) have been defined elsewhere but, taking into
account the purpose of this document it has been agreed to provide a new list of definitions, choosing those
that are most useful for the scope of the AIMESC project. The given meaning for each term is a general meaning
and the list cannot be considered exhaustive or official.
In blue a more detailed description.
Abbreviation
English term General Meaning
(when
existing)
Confirmation given by the driver to a request from the ETCS on-board
Acknowledgement ACK system that she/he has received the information she/he has to take
into account.
Different ERTMS/ETCS application levels are a way to express the
operating relationships between track and train. Level definitions are
principally related to the trackside equipment used, the way trackside
Application levels Levels information reaches the on-board units and which functions are
processed by the trackside and on-board equipment respectively. (See
Level 0, Level 1, Level 2, Level 3 and Level STM for further details.)
Automatic Train Automatic Train Control system
ATC
Control system
Automatic Train A safety system that enforces either compliance with or observation
ATP of speed restrictions and signal aspects by trains.
Protection system
Authorisation for Permission for a train to move given by means of: a trackside signal at
train movement a proceed aspect, an MA or a written order.
Transmission device (passive transponder) that can send telegrams to
Balise an On-Board subsystem passing over it. The balises in use in the
ERTMS domain are the Eurobalise.
One or more balises which are treated as having the same reference
Balise Group BG location on the track.
Balise Transmission On board equipment for intermittent transmission between track and
BTM train. This device is used to receive telegrams from balises.
Module
Information that can be sent from a balise to the On-Board subsystem.
Balise Telegram Telegram One or several telegrams constitute a balise message
Location where trains cross from one national railway network to
Border Crossing another national railway network.
A speed distance curve to be supervised in order to respect a speed
Braking Curve BC reduction.
Cab signalling provides safe movement authorities to trains; these
Cab signalling movement authorities are displayed on a device installed in the
system driver’s cab
Transparent formal and ordered processing of the changes leading to
Change Request CR a new release of the technical specifications
The set of mandatory functions defined in the FRS Version 4.29. These
Class 1 functions functions represent the minimum requirement for technical
interoperability.
Control Centre Signal box covering a large railway area, usually incorporating other
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 operational functions.
Conventional Line Conventional Line = not High Speed Line
Performer who is in charge of GSM-R communication to trains in a
Controller defined area and entitled to give orders to train drivers.
Complete mutual recognition between member States of each other’s
national rules, checking processes and authorisation. (The status
Cross Acceptance achieved by a product that has been accepted by one Authority of the
relevant European Standards and is acceptable to other Authorities
without the necessity for further assessment).
Current position The position of a train at a certain moment measured using defined
(train) system co-ordinates.
The location beyond the EOA that can be reached by the front of the
Danger Point DP train without creating a hazardous situation.
Device to record defined actions and swaps relating to the train’s
Data Recording Unit DRU movements. (The recorded data can be used for off line analysis of all
events that happened during a train journey).
Driver Person qualified and authorised to drive trains.

Driver Machine Train borne device to enable communication between ETCS/GSMR

DMI and the driver.
Interface
The driver is obliged to proceed with caution, taking into account the
Driving On Sight line visible ahead, controlling the speed such that it is possible to stop
short of any obstacle.
Supervision of the speed of the train versus its position, in order to
Dynamic speed make the train respect the Most Restrictive Speed Profile and Limit Of
monitoring Authority/End Of Authority.
Call set up in some dangerous situations to warn all trains/shunting
Emergency call EC movements in a defined area of a sitiuation requiring an immediate
response.
Emergency Train movement performed in Reversing in emergency with the driver
propelling in a cab not on the front vehicle in the direction of running.

Emergency Area where emergency propelling movements in RV are allowed.

propelling area
Emergency stop ETCS order braking a train with the maximum brake force until the
order train is at standstill.
Location to which the train is authorised to move and where the
End of Authority EoA target speed is zero.
ETCS location Harmonised trackside ETCS signal to identify a specific location on the
marker line.
Part of ETCS installed on a railway vehicle ( A Computer-based system
ETCS On–Board that supervises the movement of the train to which it belongs, on the
ETCS OBS
System basis of information exchanged with the ETCS trackside system).
Harmonised trackside ETCS signal to indicate the location where a
ETCS stop marker train running in SR has to stop.
Group of trains based on some specific characteristics of the rolling
ETCS train category stock.
ETCS trackside Part of ETCS installed trackside.
System

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 Eurobalise message is the information sent by a balise group (i.e. the
message is composed of one or several telegrams, sorted by balise
Eurobalise message number in the group (telegram from balise number 1 first), each
telegram is transmitted by a Eurobalise). A Eurobalise telegram
contains one header and an identified and coherent set of Packets
The Euroloop subsystem operates on Level 1 lines, providing signalling
information in advance as regard to the next main signal in the train
Euroloop running direction. Euroloop is composed of an on-board functionality
and by one or more trackside parts.
The mode of ETCS when running all train and track data, which is
required for a complete supervision of the train, is available on board.
Full Supervision FS It is the ETCS mode giving full protection against over speed and over
run.
Handover The process of passing a train between two Radio Block Centres.
Data that is transmitted from track to train at locations other than at
Infill information main signals. Provides, for example, the ability to inform a train that
the signal ahead has cleared.
A loop which is installed at a place (e.g. in rear of a signal) where it is
not essential for train safety, but avoids unnecessary delay by
Infill loop transmitting infill information advising the train at once when the
signal clears.
A general term applied to the controlling of the setting and releasing
Interlocking of “signals” and “points” to prevent unsafe conditions arising, and
equipment which performs this function.
The “ability of a rail system to allow the safe and uninterrupted
movement of trains which accomplish the required levels of
Interoperability performance for these lines. This ability depends on all the regulatory,
technical and operational conditions which must be met in order to
satisfy the essential requirements”.
The mode of ETCS when the ETCS system is isolated (disconnected)
Isolation IS from the other on-board equipment/systems (including the driver)
and physically isolated from the brakes.
Device to record defined data (actions and swaps) relating to the
Juridical Recording train’s movements for legal purpose. (The recorded data shall allow
JRU
Unit analysing the cause of an accident/incident/hazardous situation ).
Level of ERTMS/ETCS defined to cover instances when the train borne
equipment is operating in an area where the track side is not fitted
Level 0 L0 with operational ERTMS / ETCS equipment (train equipped with
ERTMS/ETCS operating on a line without ERTMS/ETCS or national
system or with the ERTMS/ETCS systems in commissioning).
Level of ERTMS/ETCS with or without infill transmission defined to
overlay onto conventional line side signalling (train equipped with
Level 1 L1 ERTMS/ETCS operating on a line with conventional line side signalling
equipped with Eurobalises and optionally Euroloop or Radio infill)
Level of ERTMS/ETCS that uses radio to transmit movement
authorities to the train whilst relying on conventional equipment to
determine train location (train equipped with ERTMS/ETCS operating
Level 2 L2 on a line controlled by a Radio Block Centre and equipped with
Eurobalises and Euroradio with train location and train integrity
proving performed by the trackside).
Level 3 L3 Level of ERTMS/ETCS similar to level 2 but with train location and train

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 integrity supervision based on information received from the train.
Level of ERTMS/ETCS that allows the train equipped with ERTMS/ETCS
Level STM LSTM operating on a line equipped with a national system to which it
interfaces by use of an STM.
The mode of ETCS when the ETCS enables the train to be operated in
areas where trackside information can be supplied to realise
background supervision of the train. Inside these areas with lineside
Limited Supervision LS signals, ETCS may not have information regarding the status of some
of them (e.g. not all signals are fitted with LEUs or connected to an
RBC). The driver must observe the existing line-side information
(signals, speed boards etc.) and national operating rules.
The place beyond which the train is not authorised to pass and where
Limit of Authority LoA target speed is zero.
Line side electronic units are electronic devices that generate
Line side Electronic telegrams to be sent by balises, on the basis of information received
LEU
Unit from external trackside systems.
Loop transmission Train borne equipment that reads the track mounted loop data.
LTM
module
Information sent:
a) by a balise group (it is composed of one or several telegrams);
b) by RBC (Euroradio message contains one header an identifier and
Message coherent set of variables and Packets);
c) by loop (Euroloop message contains one header an identifier and
coherent set of variables and Packets) .
Movement Permission for a train to move to a specific location with supervision
MA of the permitted speed.
Authority
The most restrictive speed restrictions the train shall obey on a given
Most Restrictive piece of track. (The lowest speed taking into account all various speed
MRSP
Speed Profile profiles)
Pre existing Train control system as defined in the Directive 96/48
National train that, in order to interface with ETCS, can be considered as a candidate
control system for a specific transmission module (STM).
Values used to configure the ETCS supervision to local (national)
National values requirements. (Those values are transmitted to a train when entering
the infrastructure of a country)
The mode of ETCS when the ETCS system is not powered. (In this
No Power NP mode the full responsibility for the safe control of the train is given to
the driver).
A line without operational track side ERTMS/ETCS equipment or with
Non equipped line the ERTMS/ETCS systems in commissioning.
The mode of ETCS used to manage the ETCS on-board equipment of a
slave engine that is not electrically coupled with the leading engine
Non Leading NL (and so, not remote controlled) but has its own driver (the active train
borne equipment and driver is not in the leading cab).
Area defined by the Infrastructure Manager where it may not be safe
Non stopping area or suitable to stop a train.
The entire process of measuring the train’s movement (speed and
Odometry distance) during a journey along the track.
Depending on the application level (see further sections), the on-
On Board sub- board sub-system can be composed of:
OBS
System a) the ERTMS/ETCS on-board equipment;
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 b) the on-board part of the GSM-R radio system;
c) specific transmission modules for existing national train control
systems.
The mode of ETCS that gives the driver full responsibility for the safe
control of his train at an enforced and limited speed (national value
On Sight OS for driving on sight) when the ETCS system enables the train to enter
into a track section that could be already occupied by another train, or
obstructed by any kind of obstacle.
Operational text Information or instructions sent to the driver for railway operational
messages purposes.

Operational Train Set of technical and/or operational characteristics of a train related to

Category the relevant ETCS speed profiles.

Override EOA speed Maximum speed when the override EOA function is active.
Packets are multiple variables grouped into a single unit, with a
Packets defined internal structure.
The speed limit at which the driver can run without ETCS warning
Permitted speed and/or intervention
Temporary speed restriction that is implemented by ETCS or included
in the list of temporary speed restrictions. (The temporary speed
Planned Temporary restriction is defined to enable a separate category of track
TSR
speed restriction infrastructure speed restriction which can be used for working areas,
etc.)
Condition reached after a train trip when the train has been brought
to a stand and after the driver’s acknowledgement of the situation. (It
Post Trip is only possible to release the brake after the driver’s
acknowledgement).
Preparation of the All tasks to be performed before a train starts to operate.
train
Movement of railway vehicles where the driver is not in the leading
cab of the leading vehicle. (When propelling, the operative cab is next
Propelling to the train being propelled and the master switch is in forward. A
train cannot propel itself (see reversing) but is able to propel another
train).
Radio Exchange of information between the on-board system and the
Communication RBC/radio infill unit.
An ETCS trackside centralised unit controlling movements of trains
fitted with ETCS on-board equipment. (The RBC is a computer-based
Radio Block Centre RBC system that elaborates messages to be sent to the train on the basis of
information received from external trackside systems and on the basis
of information exchanged with the on-board sub-systems).
A defined area where it is not possible by design to establish a reliable
Radio hole radio communication channel.
The RADIO IN-FILL subsystem operates on Level 1 lines, providing
signalling information in advance as to the next main signal in the
Radio in-fill unit train running direction. RADIO IN-FILL is composed of an on-board
functionality and by one or more trackside parts (named RADIO IN-
FILL Unit)
Radio message Is a message from train to track or from track to train via Radio

Release Speed RS A speed value which allows a train to approach the end of its
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 Movement Authority. (Needed mainly for intermittent transmission to
enable the train approach a signal that has cleared in order to reach
the information point at the signal.)
A train movement which is done in the opposite direction to the
Reverse movement planned one.
The mode of ETCS when the ETCS system allows the driver to change
Reversing RV the direction of movement of the train driving from the same cab (the
train orientation remains unchanged).
Revocation of MA Withdrawal of a previously given MA.

Route book Document or system that provides the driver with details of the line.
The mode of ETCS when running in level STM (national). This mode of
ETCS enables an STM to access, via the ETCS on board equipment, the
Running in SN SN following resources: MMI, TIU, odometer and brakes. In this mode the
operational rule to be used are national rules.
Measures to be applied to avoid unintentional movement of railway
Securing vehicles.
Service Brake First line of system intervention (service brake)
SBI
Intervention
The mode of ETCS to enable shunting movement in an equipped area.
Shunting SH (To access this mode no train data are needed).
Way of moving vehicles without train data and controlled by shunting
Shunting movement signals.
Performer in charge of the route setting of trains/shunting
Signaller movements and of issuing instructions to drivers.
The mode of ETCS used to manage the ETCS on-board equipment of a
Sleeping SL slave engine that is electrically and mechanically coupled with the
leading engine (remote controlled).
Specific
Module which allows the ETCS on-board to operate with a non ETCS
Transmission STM trackside train control system.
Module
The mode of ETCS that gives the driver full responsibility for the safe
Staff Responsible SR control of his train at an enforced and limited speed (national value
for Staff Responsible) in an equipped area.
This mode is a default mode of awakening the ETCS system and
Stand-By SB performing a self test.
The Static Speed Profile (SSP) is a description of the fixed speed
restrictions of a given piece of track. The speed restrictions can be
related to e.g. maximum line speed, curves, points, tunnel profile sand
Static Speed Profile bridges. The Static Speed Profile is based on factors, which are both
SSP
track and train dependent. The relationships between track and train
characteristics determine the individual Static Speed Profile for each
train.
The mode of ETCS in case of a fault in the ETCS on board equipment
System failure
which affects safety.
Two or more traction units mechanically and pneumatically coupled,
but not remote controlled, used in the same train and where each
Tandem traction unit requires a driver. (Only one unit is leading, the other units
are therefore non-leading).
Distance to the location where the train speed must be equal to or
Target Distance below the given target speed.

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 Speed that has to be respected at the location defined by the target
Target speed distance.
The Target Speed at the EOA is the permitted speed at the EOA; when
Target sped at the the target speed is not zero, the EOA is called the Limit of Authority
EOA (LOA). This target speed can be time limited
Specifications by which each subsystem or part of subsystem is
Technical covered in order to meet the essential requirements and to ensure
Specification for TSI the interoperability of the trans-European high speed and
Interoperability conventional rail systems.
Temporary speed Reduction of the infrastructure speed to a lower value for a time
TSR period.
restriction
Text message Information in writing displayed on the DMI.
Information which describes the characteristics of the track in order to
Track description supervise a train movement.
Trackside radio GSM-R radio communication network is used for the bi-directional
communication GSM-R exchange of messages between on-board sub-systems and RBC or
network (GSM-R) radio infill units
Depending on the application level, the trackside sub-system can be
composed of:
a) balise
b) lineside electronic unit (LEU)
Trackside subsystem c) the radio communication network (GSM-R)
d) the Radio Block Centre (RBC)
e) Euroloop
f) Radio infill unit
Traction unit Vehicle with driving cab(s) from where a movement may be operated.
One or more traction units with or without coupled railway vehicles or
Train set of vehicles with ETCS train data required.

The equipment with the responsibility of supervising vehicle operation

Train borne according to the information received from infrastructure
equipment installations, from other non ERTMS / ETCS on-board equipment, from
the driver and from the track side signalling system.
Train Category Set of technical and/or operational characteristics of a train related to
(operational) the relevant ETCS speed profiles.
Information which describes the characteristics of the train in order to
Train Data supervise a train movement.
In the context of ETCS, “train integrity” means the completeness of
Train Integrity the train.
The unit that provides the interface between the train borne
Train Interface Unit TIU equipment and the train.
Train preparer Performer in charge of the preparation of a train.

Train Type Identifier of a predefined set of train data.

Transition (Levels) Controlled change between the different ETCS levels.

Transition Point Point where a transition between ETCS levels takes place.
The mode of ETCS in case of irrevocable application of the emergency
Trip brakes by ETCS until the train/shunting movement is at a standstill. (In
this situation it is not possible to release the brake until the
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 train/shunting movement is at standstill and before the driver’s
acknowledgement of the trip).
This is the mode of ETCS that allows a fitted train to run in an unfitted
Unfitted UN area or in an area with ETCS in commissioning. (In this mode the
operational rules to be used are purely national rules).
Audible and/or visual indication to alert the driver to a condition which
requires a positive action by the driver. (If the train speed exceeds the
Warning Limit W warning limit, a warning shall be triggered, allowing the driver to
avoid brake intervention).
Written Order WO Instruction issued by the signaller to the driver.

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OTHER ABBREVIATIONS THAT CAN BE FOUND INTO THE TECHNICAL SPECIFICATION FOR ERTMS
BCA Braking Curve Area
BIU Brake Interface Unit
CR Conventional Rail
DP Danger Point
DRU Data Recording Unit
EBD Emergency Brake Deceleration
EBI Emergency Brake Intervention
EoM End of Mission
ERTMS European Railways Train Management System
ETCS European Train Control System
Eurocab (European Vital Computer) European Vital Computer (EVC)
EVC European Vital Computer
FFFIS Form Fit Functional Interface Specifications
FIS Functional Interface Specifications
FRS Functional Requirements Specification
HS High Speed
IS Isolation
LRBG Last Relevant Balise Group
TM Mobile Terminal
MA Movement Authority
MRSP Most Restrictive Speed Profile
PT Post Trip
RAM Reliability, Availability, Manutibility
RAMS Reliability, Availability, Manutibility and Safety
RMP Reverse Movement Protection
RAP Roll Away Protection
SBD Service Brake Deceleration
SMS Short Messages Service
SE Specific Transmission Module European (STM European)
SoM Start of Mission
SvL Supervised Location
SF System Failure
SRS System Requirements Specifications
TAF Track Ahead Free

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