SIST EN 17997:2025

SLOVENSKI STANDARD
01-marec-2025
Železniške naprave - Zavore - Opredelitev parametrov zavorne krivulje ETCS za
vlake Gamma
Railway applications - Braking - Definition of ETCS brake curve parameters for Gamma
trains
Bahnanwendungen - Bremsen - Bestimmung der ETCS-Bremskurvenparameter für
Gamma-Züge
Applications ferroviaires - Freinage - Détermination des paramètres des courbes de
freinage ETCS pour les trains Gamma
Ta slovenski standard je istoveten z: EN 17997:2025
ICS:
45.040 Materiali in deli za železniško Materials and components
tehniko for railway engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 17997
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2025
EUROPÄISCHE NORM
ICS 45.060.01
English Version
Railway applications - Braking - Definition of ETCS brake
curve parameters for Gamma trains
Applications ferroviaires - Freinage - Détermination Bahnanwendungen - Bremsen - Bestimmung der ETCS-
des paramètres des courbes de freinage ETCS pour les Bremskurvenparameter für Gamma-Züge
trains Gamma
This European Standard was approved by CEN on 25 November 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17997:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 6
Introduction . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, symbols and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Symbols and abbreviated terms . 10
4 ETCS on-board brake model parameters . 11
4.1 ETCS on-board emergency brake model parameters . 11
4.1.1 Nominal emergency brake deceleration A . 11
nominal
4.1.2 Correction factor K (C,V,EBCL) . 11
dry
4.1.3 Correction factor K (C,V) . 12
wet
4.1.4 Emergency brake response time . 12
4.1.5 Traction cut-off time . 12
4.2 ETCS on-board service brake model parameters . 12
4.2.1 General. 12
4.2.2 Nominal service brake deceleration A . 12
nominalSB
4.2.3 Service brake response time . 12
4.2.4 Normal service brake deceleration and correction factors K . 12
n
5 Brake system architecture model . 13
5.1 General. 13
5.2 General procedure description for K (C,V,EBCL) determination . 14
dry
5.2.1 General. 14
5.2.2 Step 1: Bottom-up functional analysis. 14
5.2.3 Step 2: Top-down impact analysis . 16
5.2.4 Step 3: Model simplification . 17
5.3 Mathematical model building. 18
6 Input data. 20
6.1 General. 20
6.2 Origin of input data . 20
6.3 Validity of input data . 21
7 Determination of ETCS emergency brake model parameters . 22
7.1 Parameters . 22
7.1.1 General. 22
7.1.2 ETCS brake parameters set approaches . 24
7.1.3 Approach dependency . 25
7.1.4 Resolution of ETCS brake parameters. 26
7.2 Nominal emergency brake deceleration . 26
7.2.1 General. 26
7.2.2 Determination by dynamic brake testing . 27
7.2.3 Determination by calculation . 33
7.2.4 Determination at degraded conditions . 34
7.2.5 Determination for multiple unit operation . 34
7.3 Correction factor K (C,V,EBCL) . 35
dry
7.3.1 General . 35
7.3.2 Determination of weighting factors α (C,V) . 37
j
7.3.3 Determination of factors β (i,C,V) . 37
j
7.3.4 Determination of factors α' (C,V) and β' (C,V) . 39
k k
7.3.5 Determination of correction factor K (C,V,EBCL) with Monte Carlo method . 40
dry
7.4 Correction factor K (C,V) . 40
wet
7.4.1 General method for determination of K (C,V) . 40
wet
7.4.2 Determination of K (C,V) for wheel/rail adhesion independent brake units . 41
wet
7.5 Emergency brake time characteristic . 42
7.5.1 General . 42
7.5.2 Multiple units operation . 42
7.6 Traction cut-off time . 43
7.6.1 General . 43
7.6.2 Multiple units operation . 44
8 Determination of ETCS service brake model parameters . 44
8.1 General . 44
8.2 Nominal deceleration for service braking . 44
8.3 Service brake response time . 44
8.4 Normal service brake deceleration and correction factors Kn . 44
9 Common set of parameters . 45
10 Validation of the calculation tool . 45
10.1 General . 45
10.2 Verification using a simplified model . 46
10.3 Validation by example calculations . 46
11 Documentation . 47
11.1 General . 47
11.2 Brake system architecture model . 47
11.3 Input data . 47
11.4 Nominal values . 47
11.5 Correction factors . 48
11.6 Source list . 48
Annex A (informative) Basic formulae for the commonly used types of brake unit . 49
A.1 General . 49
A.2 Factor β (i,C,V) . 49
j
A.2.1 Internal and external parameters for tread brake unit . 49
A.2.2 Internal and external parameters for disc brake unit . 51
A.2.3 Internal and external parameters for magnetic track brake unit . 53
A.2.4 Internal and external parameters for eddy current brake unit . 54
A.2.5 Internal and external parameters for electro-dynamic brake. 57
A.3 Factor βj’(i,C,V) . 58
Annex B (informative) Derivation of the formulae for K (C,V,EBCL) . 60
dry
B.1 General . 60
B.2 Linear and nonlinear input variables . 60
B.3 Consideration of the complete train . 62
B.4 Consideration of the structure of the train and subsystem. 63
B.4.1 General. 63
B.4.2 Higher level structure of the train and subsystem . 63
B.4.3 Structure of the control units without redundancies . 65
B.4.4 Consideration of redundancies . 66
B.4.5 Cross system variables . 68
Annex C (normative) Application of K (C,V,EBCL) formulae . 71
dry
C.1 General. 71
C.2 Example 1: 3-car EMU . 72
C.2.1 Description of the train . 72
C.2.2 Brake system architecture model . 76
C.2.3 Weighting factors . 76
C.2.4 Determination of factors βj(i,C,V) . 76
C.2.5 K (C,V) formulae . 80
i
C.2.6 Results . 81
C.3 Example 2: architecture defined in EN 14531-1 . 82
C.3.1 Description of the train . 82
C.3.2 Brake system architecture model . 85
C.3.3 Weighting factors . 86
C.3.4 Determination of factors β (i,C,V) . 87
j
C.3.5 K formulae . 88
i
C.3.6 Results . 89
Annex D (informative) Determination of K (C,V,EBCL) using the Monte Carlo method
dry
depending on the number of Monte Carlo iterations . 90
D.1 Definitions . 90
D.2 Determination of K (C,V,EBCL) depending on the number of Monte Carlo iterations
dry
................................................................................................................................................................... 90
D.3 Examples . 92
Annex E (informative) Methods for simplifying the brake system architecture model . 93
E.1 General. 93
E.2 Structure grouping . 94
E.2.1 Serial structure . 94
E.2.2 Parallel redundant structure . 95
E.2.3 Parallel branched structure . 96
E.2.4 Double failure in parallel branched structure . 97
E.3 Simplification example . 97
E.3.1 Example system . 97
E.3.2 Double failure check . 98
E.3.3 Grouping of parallel branched structure . 99
E.3.4 Grouping of parallel redundant structure . 100
E.3.5 Grouping of serial structure . 102
E.4 Extended description of the methods mentioned in 5.2.4 . 103
E.4.1 S-1 Grouping of components and technical functions . 103
E.4.2 S-2 “Worst case consideration”. 104
E.4.3 S-3 Neglection of highly improbable event. 105
E.4.4 S-4 Reduction of model levels . 105
E.4.5 S-5 Assumption of permanently failed components . 106
Annex F (informative) Determination of the failure probability by FIT rate analysis . 107
F.1 General . 107
F.2 Conversion of FIT rates into failure probability. 107
Annex G (informative) Simplified model, used for the validation of a calculation tool . 108
G.1 General . 108
G.2 Train model . 108
G.2.1 General . 108
G.2.2 Statistical data for pneumatic brake . 111
G.2.3 Statistical data for magnetic track brake . 112
G.2.4 Statistical data for electro-dynamic brake . 112
G.2.5 Statistical data for traction units . 113
G.3 Examples of validation of the correct use of parameter information . 113
G.3.1 Mass deviation . 113
G.3.2 Wheel diameter deviation . 113
G.3.3 MTB brake force deviation . 114
G.3.4 ED brake force deviation . 114
G.3.5 Failure probability of traction cut-off . 115
G.4 Example of verification of the correct use of structural information . 115
G.4.1 Failure probability on bogie level for pneumatic brake . 115
G.4.2 Failure probability on vehicle type level for MTB . 115
Bibliography . 117

European foreword
This document (EN 17997:2025) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by July 2025, and conflicting national standards shall be
withdrawn at the latest by July 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website. According to the CEN-CENELEC
Internal Regulations, the national standards organisations of the following countries are bound to
implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania,
Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United Kingdom.
Introduction
European Train Control System (ETCS) specifications have become part of, or are referred to the
Technical Specifications for Interoperability (TSI) for railway control-command systems, as part of the
European legislation, managed by the European Union Agency for Railways (ERA).
The Braking model specification in this document is based on the definition in the System Requirements
Specification (SRS) SUBSET-026, Version 3.6.0 of 13/05/2016 [11], published by the European Union
Agency for Railways: ETCS B3 R2 GSM-R B1 [10].
Based on a generic “brake system architecture model” a procedure is described to design a train specific
software model which is applied for calculating the rolling stock correction factors and a method for
determination of the nominal emergency and service braking deceleration for normal and degraded
modes is described. Furthermore, the derivation of all the required traction and braking model
parameters is specified.
This document describes the different steps to define ETCS emergency and service brake parameters for
ETCS gamma braking model trains intended to operate on lines equipped with ETCS Baseline 3 [10].
1 Scope
This document specifies the methodology to define the train related braking model and required
emergency and service brake on-board parameters to enable speed and distance monitoring for trains
equipped and operated on railway lines using ETCS Baseline 3.
This document is only applicable for ETCS Gamma braking model trains (i.e. the train is said to be a
“gamma” train). This document does not specify the way these parameters are transferred to and can be
used by the ETCS on-board system (e.g. during start of mission - SoM).
The ETCS “conversion models” are not covered by this document and are described in EN 16834:2019,
Annex F. The ETCS “conversion models” are intended for use with trains where the braking performance
is expressed using braked weight percentages (“lambda” train).
Any trackside related input parameters, including national values, are not covered in this document.
Information can be found in the SUBSET-026 (see [11]).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 15595:2018+A1:2023, Railway applications — Braking — Wheel slide protection
EN 16834:2019, Railway applications - Braking - Brake performance
EN 17343:2023, Railway applications - General terms and definitions
EN 50126-2, Railway Applications - The Specification and Demonstration of Reliability, Availability,
Maintainability and Safety (RAMS) - Part 2: Systems Approach to Safety
EN ISO 24478:2024, Railway applications — Braking — General vocabulary (ISO 24478:2023)
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 17343:2023,
EN ISO 24478:2024 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1.1
base unit
smallest considered unit of a certain system on the lowest level of the level model
3.1.2
building block
validated information for the characteristics of a brake sub-system (e.g. Magnetic Track Brake), that is
derived from the difference between test results of configurations with and without the brake sub-system
3.1.3
highly improbable event
event which is extremely unlikely to occur and can be neglected
Note 1 to entry: See also EN 50126-1:2017, Table C.1 [5].
3.1.4
brake system architecture model
calculation model for some ETCS brake parameters which can be applied for Kdry definition with Monte
Carlo simulation
3.1.5
level model
model that enables the consideration of structural information of the vehicle in the brake system
architecture model
3.1.6
technical function
function, which can be generated by a single component or a complete system
Note 1 to entry: The technical function of the brake system is to generate braking force.
3.1.7
structural information
information about the levels, units and structure used in a brake system
3.1.8
statistical information
information that describes the failure or/and the deviation behaviour of a technical function
3.1.9
failure coefficient
coefficient that represents the effect of the failure of a technical function on the braking force of a brake
unit/group of brake units and is linked to the probability of failure of the technical function
3.1.10
deviation coefficient
coefficient that represents the effect of the deviation of a technical function on the braking force of a brake
unit/group of brake units and is linked to the statistical distribution of deviation of the technical function
3.1.11
normal mode
operating condition with all expected brakes available and performing as specified
[SOURCE: ISO 24221:2024, 3.6]
3.1.12
degraded mode
operating condition where some of the brakes are not available and/or not performing as specified (e.g.
equipment failure, leakage)
[SOURCE: ISO 24221:2024, 3.7]
3.1.13
car
type of vehicle (e.g. trailer car, motor car)
Note 1 to entry: A trailer car can be a coach or a wagon, a motor car can be a locomotive.
3.2 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in Table 1 apply.
Table 1 — Symbols and abbreviated terms
Symbol Definition Unit
safe emergency brake deceleration, also called A_brake_safe in
A (C,V,EBCL) m/s
brake safe
SUBSET-026–3 [11]
A (C,V,EBCL) safe emergency brake deceleration on dry rails m/s
brake safe dry
nominal deceleration in emergency brake, also called
A (C,V) m/s
nominal
A_brake_emergency in SUBSET-026–3 [11]
nominal deceleration in service brake, also called A_brake_service
A (C,V) m/s
nominalSB
in SUBSET 026-3 [11]
normal service brake deceleration, also called A_brake_
A (C,V) m/s
normal
normal_service in SUBSET-026–3 [11]
identification of the configuration of the brakes (combination of
C special brake, degraded modes with brakes isolated, multiple unit —
operation, etc.)
F braking force N
K (C,V,EBCL) correction factor, also called Kdry_rst in SUBSET-026–3 [11] —
dry
correction factor for one random selected combination “i” (also
K (C,V) called case “i”) of parameters (influencing braking force and failure —
i
behaviour) for calculation of deceleration
speed dependent correction factors for gradient on the normal
K (V) —
n
(V) (uphill) and K (V) (downhill)
service brake; split in Kn+ n-
K (C,V) correction factor, also called Kwet_rst in SUBSET-026–3 [11] —
wet
P probability of failure —
equivalent emergency brake response time, also called
t (C) s
eEB
T_brake_emergency (for emergency brake) in SUBSET-026–3 [11]
equivalent service brake response time, also called T_brake_service
t (C) s
eSB
(for service brake) in SUBSET-026–3 [11]
traction cut-off time, also called T_traction_cut_off in SUBSET-026–
t (C) s
tco
3 [11], 3.13.2.2.2
V identification of the speed interval —
V maximum design speed of the train —
max
weighting factor representing the part of a brake unit/group of
α —
brake units/brake type force in the total braking force
Symbol Definition Unit
ratio of the maximum force generated by a traction unit compared
α' —
to the total braking force at train level
factor representing the product of the impact of all deviations and
β —
failure impacting the braking force of a brake unit
factor representing the impact of possible traction cut-off failures
β' leading to a reduction of total braking force by generation of a —
traction force
—
BCU brake control unit
—
DBU disc brake unit
—
EBCL emergency brake confidence level
—
ECB eddy current brake
—
ED electro-dynamic brake
—
ETCS European Train Control System
—
FIT failures in time
—
MTB magnetic track brake
function providing a random value depending on a distribution
—
Rnd
type and on parameters
—
B Bernoulli distribution
—
N Normal distribution
—
U Uniform distribution
—
TBU tread brake unit
—
WSP wheel slide protection
4 ETCS on-board brake model parameters
4.1 ETCS on-board emergency brake model parameters
4.1.1 Nominal emergency brake deceleration A
nominal
A (C,V) is the established deceleration during an emergency braking for a given configuration of the
nominal
train for a defined speed interval (see SUBSET-026-3 [11] and SUBSET-040 [12]). The determination of
A is described in 7.2.
nominal
4.1.2 Correction factor K (C,V,EBCL)
dry
K (C,V,EBCL) is a rolling stock correction factor that, applied to A , gives the safe emergency brake
dry nominal
deceleration for a given configuration of the train, on dry rails in accordance with the required confidence
level, and for a defined speed interval (see SUBSET-026-3 [11] and SUBSET-040 [12]).
A C,,V EBCL KA C,,V EBCL× C, V (1)
( ) ( ) ( )
brake safe dry dry nominal
The determination of K (C,V,EBCL) is described in 7.3.
dry
=
4.1.3 Correction factor K (C,V)
wet
K (C,V) is a rolling stock correction factor that considers in a limited way the loss of deceleration with
wet
regards to emergency braking on dry rails, when the emergency brake is applied on low adhesion rails,
in accordance with wheel/rail adhesion reference conditions, and for a defined speed interval (see
SUBSET-026-3 [11] and SUBSET-040 [12]).
A C,,V EBCL KMC, V+ ×−1 K C, V× A C,,V EBCL (2)
( ) ( ) ( ) ( )
( ( ))
brake safe wet NVAVADH wet brake safe dry
NOTE MNVAVADH is a trackside ETCS parameter and is not in the scope of this document.
The determination of K (C,V) is described in 7.4.
wet
4.1.4 Emergency brake response time
The equivalent emergency brake response time t (see 7.5) is used to model the transition between the
eEB
emergency brake demand and the fully established emergency braking force (see SUBSET-026-3 [11]
and SUBSET-040 [12]).
4.1.5 Traction cut-off time
The traction cut-off time t (see 7.6) is used to model the transition between the emergency brake
tco
demand or traction cut-off demand and the moment the acceleration due to traction (A_traction) is zero
after a trainwide control signal for an emergency brake application.
4.2 ETCS on-board service brake model parameters
4.2.1 General
The service brake performance is not safety relevant. Therefore, no worst-case conditions (e.g. correction
factors, adhesion conditions) are considered for its calculation.
4.2.2 Nominal service brake deceleration A
nominalSB
A (C,V) is the established deceleration during a full service braking for a given configuration of the
nominalSB
train for a defined speed interval (see SUBSET-026-3 [11]).
The determination of A is described in 8.2.
nominalSB
4.2.3 Service brake response time
The equivalent service brake response time t (see 8.3) is used to model the transition between the full
eSB
service brake demand and the fully established service brake braking force (see SUBSET-026-3 [11]).
4.2.4 Normal service brake deceleration and correction factors K
n
The normal service brake deceleration A (C,V) is used in combination with the speed dependent on-
normal
board correction factors for gradient K +(V) and K -(V) to calculate A (V,d). This deceleration is
n n normal_service
used to calculate the guidance curve (GUI), which is an optional braking curve in ETCS (see SUBSET-026-
3 [11]).
Recommendations for determining A are described in 8.4.
normal
=
5 Brake system architecture model
5.1 General
The term “brake system architecture model” describes the model, which is applied when calculating the
correction factor K (C,V,EBCL), and which is consistent with the determination of the nominal
dry
decelerations.
For this purpose, the brake system architecture model is a set of formulae and algorithms formed from
parameters that influence braking performance.
The parameters consider both statistical and structural information related to braking.
The structural information depends on the specific vehicle architecture. The structural information
shows how many brake units are affected when a specific parameter deviates or fails.
The statistical information contains both the probability and impact of a failure of a component
(considering the structural information) and the behaviour of its deviation from the nominal values.
Both information elements are to be considered in the generation of the brake system architecture model.
The following clauses describe the steps to be followed for building a brake system architecture model
representative of the real performance of the train, from a braking point of view.
The steps are organized to avoid missing any component in the brake system architecture model that can
have an impact on the braking performance of the train.
The process is suitable for both new and existing vehicles or trains. Examples of the process are given in
Annex C.
The technical scope of the model is determined by the components that are considered in the brake
system architecture model. The intention is to consider all relevant impacts on the braking performance.
The definition of train related brake model includes all the parameters with influence on the braking
performance. These parameters are not limited to the braking system, but can also come from other
systems, such as power supply, vehicle control and the traction system.
Brake system components need energy to provide braking force. This energy is usually stored. There are
pressure vessels or batteries for this purpose. Within the scope is the brake energy storage of the systems.
Outside the scope are the systems that recharge the brake energy storage (e.g. compressors, generators).
The capacity of the brake system energy storage is usually dimensioned in such a way that minimum one
braking application under any condition (environmental, load, speed, etc.) can be carried out without
recharging. If this is not possible, the scope also refers to the systems for charging the brake system
energy storages.
If a system operates without brake system energy storage, the systems for providing the energy are
within the scope of this document.
Another consideration limit results from the maximum resolution that is achieved with the calculation
model. The smallest unit is the so-called “base unit”. It leads to the maximum resolution of the model.
If relevant influences below the base unit are worked out within the framework of the technical analysis,
these shall be considered in a suitable manner (see “model simplification” 5.2.4).
The brake system architecture model considers random failures and deviations of braking force relevant
components. Systematically caused failures of technical functions or components are not considered.
These are, among others, errors in construction documents or design documents.
Errors due to incorrect programming of software components are also included to systematically caused
failures. These systematically caused errors shall be excluded by other suitable measures, such as design
reviews or quality controls. Systematically caused failure of software shall be managed in accordance
with EN 50126-2.
5.2 General procedure description for Kdry(C,V,EBCL) determination
5.2.1 General
The process is split in 3 steps as presented in Figure 1.

Figure 1 — General process description for the development of the brake system architecture
model
In mandatory step 1, the functional analysis helps to define each brake component’s position on the right
level in the train and relations between them.
The mandatory step 2 based on impact analysis avoids missing any components which are not directly
related to brake performance but can have an impact in case of failure or deviation.
The optional step 3 permits simplification of the brake system architecture model based on the behaviour
of the components and the maintenance processes applied, to limit the mathematical model to the
necessary extend to reduce computation time.
All the steps shall be documented to justify the representativeness of the model (see Clause 11).
5.2.2 Step 1: Bottom-up functional analysis
This step is based on the functional behaviour of the train. The aim is to represent all the brake
components involved in emergency braking on the correct level in the train and draw functional links
between them.
The process should start by identification of the sub-system generating braking forces (emergency brake
units), their parameters and their location/level on the train (component level, bogie level, etc.).
Figure 2 gives an example of the first analysis.
Key
a electric power supply/air supply/internal deviations and failures
b coefficient of friction/efficiency/brake cylinder pressure/wheel diameter
Figure 2 — Example of sub-systems generating braking forces located on right level of the train
For each brake unit identified, an analysis shall be performed to determine the different components
po
...