IEC TR 62055-21:2005

Electricity metering - Payment systems - Part 21: Framework for standardization

sets out a framework for the integration of standards into a system specification for electricity payment metering systems. It addresses the payment metering system application process, generic processes, generic functions, data elements, system entities and interfaces that exist in present payment metering systems.

General Information

• Status: Published
• Publication Date: 10-Aug-2005
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: TC 13 - Electrical energy measurement and control
• Drafting Committee: WG 15 - TC 13/WG 15
• Current Stage: PPUB - Publication issued
• Start Date: 31-May-2005
• Completion Date: 11-Aug-2005

Overview

IEC TR 62055-21:2005 - "Electricity metering - Payment systems - Part 21: Framework for standardization" provides a structured framework for integrating standards into a system specification for electricity payment metering systems. The technical report defines the application process, generic processes, generic functions, data elements, and system entities and interfaces that exist in current payment metering systems, enabling consistent specification, interoperability and procurement.

Key Topics and Requirements

• Generic entity model and application process reference model for payment metering systems, describing roles and interactions between system components.
• Generic functions (e.g., metering, accounting, receipting, security, time, display, recording, data exchange) and their sub-classifications to support modular system design.
• Generic processes such as supply agreement, meter reading, billing, payment receipting, token vending, and system testing that form the lifecycle of a payment metering application.
• Data elements and records required for transactions, tokens and meter configuration to ensure consistent data exchange and auditing.
• System entities and interfaces including CIS (Customer Information System), POS (Point Of Sale), Token_Carrier, Token_Carrier_to_Meter and POS_to_Token_Carrier interfaces, and the Payment_Meter, specifying interaction points for interoperability.
• Example specification and annex showing how to derive requirements from an existing system and how to map functions, records and interfaces into a cohesive specification.
• Emphasis on security, time synchronization and testability as foundational requirements for reliable payment metering implementations.

Applications and Practical Value

IEC TR 62055-21 is a practical framework used to:

• Develop vendor-neutral system specifications for prepayment and postpaid electricity metering.
• Guide integration between meters, token vending systems, POS terminals and utility back-office systems.
• Support interoperability and procurement by defining common functions, interfaces and data elements.
• Inform testing, certification and compliance activities by enumerating processes and function classes.
• Assist utilities, system integrators and manufacturers in designing scalable, auditable payment metering solutions.

Who Should Use This Standard

• Electricity utilities and metering service providers
• Meter manufacturers and embedded system designers
• POS and token vending solution vendors
• System integrators and software developers for CIS/back-office systems
• Test laboratories, regulators and standards committees

Related Standards

• Part of the IEC 62055 series (payment metering standards). Use this framework in combination with other applicable IEC metering standards and local regulatory requirements when specifying or deploying payment metering systems.

Keywords: IEC TR 62055-21, electricity metering, payment metering systems, payment meter, token carrier, point of sale (POS), Customer Information System (CIS), metering standard, framework for standardization.

Standards Content (Sample)

TECHNICAL IEC
REPORT TR
62055-21
First edition
2005-08
Electricity metering – Payment systems –
Part 21:
Framework for standardization
Reference number
IEC/TR 62055-21:2005(E)
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
base publication incorporating amendment 1 and the base publication incorporating
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TECHNICAL IEC
REPORT TR
62055-21
First edition
2005-08
Electricity metering – Payment systems –
Part 21:
Framework for standardization
 IEC 2005  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale XE

International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – TR 62055-21  IEC:2005(E)
CONTENTS
FOREWORD.6
INTRODUCTION.8
1 Scope.9
2 References.9
3 Terms and definitions .10
3.1 Definitions .10
3.2 Abbreviated terms .12
3.3 Notation and terminology.13
4 General concepts .14
5 The generic entity model .15
6 Generic functions and application process reference model for the
Payment_Metering_System .16
6.1 Reference model .16
6.2 Business functions .17
6.3 Support functions .18
6.4 Business processes.18
6.5 Support processes .19
6.6 Payment_Metering_Application process .20
7 Framework for standardization .22
7.1 Generic processes .23
7.2 Generic functions .23
7.3 Data elements .23
7.4 System entities and interfaces.23
8 Example specification for a payment metering system .25
9 Future aspects .25
10 Generic processes.25
10.1 Class 1: Supply_Agreement process.27
10.2 Class 2: Purchase_Agreement process.27
10.3 Class 3: Account_Configuration process.27
10.4 Class 4: Metering_Configuration process.27
10.5 Class 5: Delivery_Configuration process.27
10.6 Class 6: Connection_Authorization process .27
10.7 Class 7: Transmission_Delivery process.27
10.8 Class 8: Distribution_Delivery process.27
10.9 Class 9: Installation_Connection process.27
10.10 Class 10: Point_Of_Delivery_Connection process.27
10.11 Class 11: Customer process_Delivery.28
10.12 Class 12: Meter_Reading process .28
10.13 Class 13: Customer_Billing process.28
10.14 Class 14: Payment_Receipting process .28
10.15 Class 15: Receipt_Issuing process .28
10.16 Class 16: Credit_Transfer process.28
10.17 Class 17: Delivery_Regulation process.28
10.18 Class 18: Supplier_Settlement process.29
10.19 Class 19: Time_Provision process .29
10.20 Class 20: System_Testing process .29

TR 62055-21  IEC:2005(E) – 3 –
10.21 Class 21: Information_Display process .29
10.22 Class 22: Information_Recording process .29
10.23 Class 23: Data_Exchange process .29
10.24 Class 24: Security_Enforcement process .29
11 Generic Functions .29
11.1 Class 1: Supplier function .30
11.2 Class 2: Customer function.30
11.3 Class 3: Contract function.31
11.4 Class 4: Generation function.31
11.5 Class 5: Transmission function .31
11.6 Class 6: Distribution function .32
11.7 Class 7: Metering function .32
11.8 Class 8: Delivery function .33
11.9 Class 9: Accounting function.34
11.10 Class 10: Receipting function .35
11.11 Class 11: Settlement function .35
11.12 Class 12: Time function .35
11.13 Class 13: Test function .36
11.14 Class 14: Display function .36
11.15 Class 15: Recording function .36
11.16 Class 16: Data_Exchange function .37
11.17 Class 17: Security function .37
11.18 Function_Object.38
12 Data elements .39
13 System entities and interfaces .41
13.1 CIS: Customer_Information_System .42
13.2 CIS_to_POS_Interface .42
13.3 POS: Point_Of_Sale.42
13.4 POS_to_Token_Carrier_Interface.43
13.5 Token_Carrier .44
13.6 Token_Carrier_to_Meter_Interface .45
13.7 Payment_Meter .47

Annex A (informative)  Example of a requirements specification for an electricity
payment metering system based on an existing system .57
A.1 Scope.57
A.2 Definitions .57
A.3 Customer_Information_System.57
A.4 CIS_to_POS_Interface .61
A.5 Point of sale .63
A.6 POS_to_Token_Carrier_Interface.69
A.7 Token_Carrier .80
A.8 Token_Carrier_to_Meter_Interface .80
A.9 Payment meter .87

INDEX .101

– 4 – TR 62055-21  IEC:2005(E)

Figure 1 – General concepts of a Payment Metering System .14
Figure 2 – Generic entity model for electricity payment metering systems.15
Figure 3 – Generic function model and application process for payment metering
systems .16
Figure 4 – Framework for standardization in electricity payment metering systems .22
Figure 5 – Sub-classification of the Token_Carrier_to_Meter_Interface functions.45
Figure 6 – Functional block diagram of a single-part payment meter installation .47
Figure 7 – Payment meter core functions and application process .48
Figure 8 – Sub-classification of the Accounting functions.50
Figure 9 – Sub-classification of the Metering functions.52
Figure 10 – Sub-classification of the Delivery functions .53
Figure 11 – Sub-classification of the Time functions .55
Figure A.1 – Meter_Key and Token_Data_Block generation process.73

Table 1 – Generic business functions .18
Table 2 – Generic support functions.18
Table 3 – Generic business processes.19
Table 4 – Generic support processes.19
Table 5 – Definition of generic process classes .26
Table 6 – Definition of generic function classes .30
Table 7 – Examples of security function attributes .37
Table 8 – Attributes of the Function_Object .38
Table 9 – Example of a Real_Time_Clock function object .38
Table 10 – Attributes of a Data_Object .39
Table 11 – Examples of records used in payment metering systems .40
Table 12 – Examples of application layer functions .42
Table 13 – Examples of POS functions .43
Table 14 – Examples of application layer token types .44
Table 15 – Sub-classification of the Token_Carrier_to_Meter_Interface functions .46
Table 16 – Generic processes employed by the payment meter application process .49
Table 17 – Sub-classification of the Accounting functions .51
Table 18 – Main attributes of the Accounting functions .52
Table 19 – Main attributes of the Metering functions .52
Table 20 – Sub-classification of the Delivery functions.54
Table 21 – Main attributes of the Delivery functions .55
Table 22 – Sub-classification of the Time functions.55
Table 23 – Main attributes of the Time functions .56
Table A.1 – Recording function records .58
Table A.2 – Example of Meter_record attributes.61
Table A.3 – Records to be downloaded from the CIS to the POS .61
Table A.4 – Records to be uploaded from the POS to the CIS.62
Table A.5 – Payment types .64
Table A.6 – Transaction types.64

TR 62055-21  IEC:2005(E) – 5 –
Table A.7 – Classification of POS token vending capability.65
Table A.8 – Data elements to be recorded .68
Table A.9 – Example of a transaction record.68
Table A.10 – Definition of control field .70
Table A.11 – Data elements used in tokens .72
Table A.12 – Definition of the Meter_Key_Generation function.73
Table A.13 – Data elements in the PAN_Block.74
Table A.14 – Data elements in the CONTROL_Block .74
Table A.15 – Vending Key_Types .74
Table A.16 – Meter Key_Types .75
Table A.17 – Definition of the set_ED_Key_Token_Data_Block_Generation function .75
Table A.18 – Data elements associated with the Vending_Key .77
Table A.19 – Data elements associated with the Meter_Key .77
Table A.20 – Definition of the Class_0_Class_2_Token_Data_Block_Generation
function.77
Table A.21 – Definition of the Class_1_Token_Data_Block_Generationfunction.78
Table A.22 – Definition of the Set_ED_Key_Token_Extraction function.81
Table A.23 – Definition of the Class 0 and Class 2 token extraction function.82
Table A.24 – Definition of the Class_1_Token_Extraction function .83
Table A.25 – Definition of the Metering function.89
Table A.26 – Definition of the Cumulative_Total_Register.92
Table A.27 – Definition of the Delivery function.93
Table A.28 – Definition of the Accounting function .98
Table A.29 – Definition of the Accounting register.100

– 6 – TR 62055-21  IEC:2005(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICITY METERING –
PAYMENT SYSTEMS –
Part 21: Framework for standardization

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
Technical reports do not necessarily have to be reviewed until the data they provide are
considered to be no longer valid or useful by the maintenance team.
IEC 62055-21, which is a technical report, has been prepared by Technical Committee 13:
Equipment of electrical energy measurement and load control.

TR 62055-21  IEC:2005(E) – 7 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
13/1318A/DTR 13/1325A/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 62055 consists of the following parts, under the general title Electricity metering –
Payment systems:
Part 21: Framework for Standardization
Part 31: Particular requirements – Static payment meters for active energy (classes 1 and 2)
Part 41: Standard Transfer Specification – Application layer protocol for one-way token
carrier systems
Part 51: Standard Transfer Specification – Physical layer protocol for one-way numeric and

magnetic card token carriers
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – TR 62055-21  IEC:2005(E)
INTRODUCTION
There is widespread activity in the application and development of payment metering systems
in IEC member countries. Whilst there are many similarities in equipment functionality and
operation of electricity payment metering systems in these countries, there is divergence in
the particular payment technology used as well as in the use of particular token carrier
technologies. An example of this is the large number of solutions using disposable magnetic
cards.
A need has been identified to describe the various systems and their elements in a coherent
manner and to provide a framework for standardization of payment metering systems, their
elements and interfaces.
This technical report thus seeks to meet the following objectives:
a) to present a systematic methodology to follow for use by suppliers to produce
requirements specifications for system procurement;
b) to present a systematic methodology to follow for use by equipment manufacturers to
produce specifications for systems and products;
c) to present a standard way in specifying system requirements or functionality in order that
such specifications may be easily compared and evaluated by manufacturers and users;
d) to ensure that such specifications are produced in an “open” format to allow the
interoperability of sub-system components.
It has to be noted that it is not the intention of this technical report that there should be only
one standard for payment metering systems or sub-systems, but that it should provide
guidelines for defining several such standards according to the specific needs of the industry
as and when these are identified.
The standardization work of TC13 WG15 should follow the guidelines given in this technical
report in order to present such standards in a coherent and systematic way that meets the
above objectives.
The IEC 62055 series covers payment systems, encompassing the customer information
systems, point of sales systems, token carriers, payment meters and the respective interfaces
that exist between these entities.

TR 62055-21  IEC:2005(E) – 9 –
ELECTRICITY METERING –
PAYMENT SYSTEMS –
Part 21: Framework for standardization

1 Scope
This technical report sets out a framework for the integration of standards into a system
specification for electricity payment metering systems. It addresses the payment metering
system application process, generic processes, generic functions, data elements, system
entities and interfaces that exist in present payment metering systems. The approach taken in
the framework is sufficiently generic to payment metering systems so that it should be equally
applicable to future systems.
NOTE 1 This technical report excludes the application of coin-operated meters in payment systems.
NOTE 2 This technical report specifically covers electricity metering payment systems. However, it is recognised
that payment metering is an established requirement in other utility services and the general framework for
standardization in this technical report can be applied to such other utility services.
NOTE 3 Contract functions are confined to single bi-lateral supply agreements between a supplier and a customer
and specifically exclude related third party agreements such as may be found in the deregulated markets.
NOTE 4 Future aspects are considered in Clause 9.
2 References
IEC 60050-300: International Electrotechnical Vocabulary (IEV) – Electrical and electronic
measurements and measuring instruments – Part 311: General terms relating to
measurements – Part 312: General terms relating to electrical measurements – Part 313:
Types of electrical measuring instruments – Part 314: Specific terms according to the type of
instrument
IEC 62051:1999, Electricity metering – Glossary of terms
IEC 62055-31, Electricity metering – Payment systems – Part 31: Particular requirements –
Static payment meters for active energy (classes 1 and 2)
IEC/PAS 62055-41:2003, Electricity Metering – Payment metering systems – Part 41:
Standard Transfer Specification
 NRS 009-6-6: Interface Standards – Standard Transfer Specification / Credit
dispensing unit – Electricity dispenser – Categories of tokens and transaction data fields
 NRS 009-6-7: Interface Standards – Standard Transfer Specification / Credit
dispensing unit – Electricity dispenser – Token encoding and data encryption and
decryption
 NRS 009-6-8: Interface Standards – Standard Transfer Specification / Disposable
magnetic token technology – Token encoding format and physical token definition
 NRS 009-6-9: Interface Standards – Standard Transfer Specification / Numeric token
technology – Token encoding format and physical token definition
 NRS 009-7: Standard transfer specification / The management of cryptographic keys
———————
To be published.
– 10 – TR 62055-21  IEC:2005(E)
IEC 62055-41, Electricity Metering – Payment metering systems – Part 41: Standard Transfer
Specification – Application layer for one-way token carrier systems
IEC 62055-51, Electricity Metering – Payment metering systems – Part 51: Standard Transfer
Specification – Physical layer for one-way numeric and magnetic card token carrier systems

IEC 62056-21:2001, Electricity metering – Data exchange for meter reading, tariff and load
control – Part 21: Direct local data exchange
IEC 62056-46:2002, Electricity metering – Data exchange for meter reading, tariff and load
control – Part 46: Data link layer using HDLC protocol
IEC 62056-47, Electricity metering – Data exchange for meter reading, tariff and load control
– Part 47: COSEM transport layers for IPv4 networks
IEC 62056-53:2002, Electricity metering – Data exchange for meter reading, tariff and load
control – Part 53: COSEM application layer
IEC 62056-61:2002, Electricity metering – Data exchange for meter reading, tariff and load
control – Part 61: Object identification system (OBIS)
3 Terms and definitions
For the purposes of this document, the definitions and terms given in IEC 60050-300,
IEC 62051, IEC 62055-31 and the following terms apply.
Where there is a difference between the definitions in this technical report and those
contained in other referenced IEC standards, then those defined in this technical report shall
take precedence.
3.1 Definitions
3.1.1
token
subset of data elements, containing information that is present in the APDU of the application
layer of the POS_to_Token_Carrier_Interface, and which is also transferred to the meter by
means of a token carrier, and which is finally presented to the meter application process
The converse is also true in the case of a token being sent from the meter to the POS.
3.1.2
token carrier
medium that is used in the physical layer of the POS_to_Token_Carrier_Interface, onto which
the token is modulated or encoded, and which serves to carry the token from the point where
it is generated to the remote meter, where it is received
3.1.3
location
geographical area, clearly distinguishable from another adjacent area, on which the payment
meter is installed
Examples of such locations are: consumer’s premises, building, street or pavement.

TR 62055-21  IEC:2005(E) – 11 –
3.1.4
local
term defined in relation to the physical location of the payment meter installation
Any device that is on the same location as the payment meter is considered to be local.
3.1.5
remote
term defined in relation to the physical location of the payment meter installation
Any device that is not on the same location as the payment meter is considered to be remote.
3.1.6
supplier
legal entity that enters into a contractual supply agreement with a customer to effect delivery
of electrical energy or other utilities
NOTE Other definitions of “supplier” may be relevant in deregulated markets.
3.1.7
transaction record
group of data elements describing the necessary attributes of a financial transaction
This would normally include items like transaction amount, purchase item identifier, kWh
value, payment type, receipt number, customer reference number, operator number, shift
batch number, sales batch number, banking batch number, etc.
3.1.8
shift batch
group of transaction records created during a single working shift of a particular POS operator
3.1.9
shift batch summary
summary of transactions in a shift batch, summarized by transaction type and optionally by
service type and by the supplier
NOTE It is common practice for an agent to perform the receipting function for several supply companies, thus
requiring transaction records to be separated per supplier. A single supplier such as a municipality that supplies
water and electricity also requires transaction records to be separated per service type.
3.1.10
sales batch
group of shift batches
3.1.11
sales batch summary
summary of transactions in a sales batch, summarized by shift batch and by transaction type
and optionally by service type and by the supplier
3.1.12
banking batch
group of sales batches
3.1.13
banking batch summary
summary of transactions in a banking batch, summarized by sales batch, by shift batch and
by transaction type and optionally by service type and by the supplier.
It includes bankable amounts totalled by payment type (and optionally by service type and by
the supplier) in preparation for bank depositing and settlement with each supplier.

– 12 – TR 62055-21  IEC:2005(E)
3.1.14
process
logically linked sequence of tasks that enables the system to achieve particular objectives
For definition of various processes, see Clause 10.
3.1.15
function
encapsulation of a defined capability or functionality of the system
For definition of various functions, see Clause 11.
3.2 Abbreviated terms
3DES Triple DES (see also DES); Data Encryption Standard applied 3 times
AES Advanced Encryption Standard
AMR Automatic Meter Reading
APDU Application Protocol Data Unit
ASN Abstract Syntax Notation
BS British Standard
CDROM Compact disc read-only memory
CDU Credit Dispensing Unit (see also POS)
CIS Customer_Information_System
CRC Cyclic_Redundancy_Code
CRT Cathode-ray tube
C/S Client / Server
DES Data Encryption Standard
DIN Deutsches Institut für Normung; a Germany-based standards organization
DLMS Device Language Message Specification
ED Electricity Dispenser or Energy Dispenser; used in Annex A interchangeably
with “meter”
GMT Greenwich Mean Time
GPRS General Packet Radio Service
GSM Global System for Mobile communications
HO high-order portion of a number
HTML Hyper Text Mark-up Language; a standard format for web documents
ID Identifier or identification
IEC International Electrotechnical Commission
IEC/PAS IEC – Publicly Available Specification
ISO International Standards Organization
kWh kilo-watt hour
LAN Local Area Network
LCD Liquid-crystal display
LED Light emitting diode
LO low-order portion of a number

TR 62055-21  IEC:2005(E) – 13 –
NRS National Rationalized user Specification; a South African industry standard
OSI Open System Interconnection; a reference model for communication protocols
PAN Primary_Account_Number
PLC Power Line Carrier
POD Point_Of_Delivery
POS Point_Of_Sale (see also CDU)
PSTN Public Switched Telephone Network
RAM Random Access Memory
RAS Remote Access Server
RSA A public key cryptography standard; Authors: Rivest, Shamir and Adelman
STS Standard Transfer Specification
STT Standard Token Translator; converts an STS format token into a specified
proprietary format token
TC13 IEC Technical Committee 13
TCP/IP Transmission Control Protocol / Internet Protocol
TID Token_Identifier
TV Television
WAN Wide Area Network
WG15 Working Group 15 of IEC TC13
X.25 A standard for packet switching networks; layers 1, 2 and 3 in OSI model
XML Extensible Mark-up Language; a standard format for data exchange

3.3 Notation and terminology
Throughout this technical report the following rules are observed regarding the naming of
terms:
• entity names, data element names, function names and process names are treated as
generic object classes and are given names in terms of nouns, which are capitalized and
joined with an underscore to signify a single entity. Examples are: Supply_Group_Code as
a data element name, Encryption_Algorithm as a function name and Installation_
Connection as a process name;
• direct (specific) reference to a named class of object uses the capitalized form, while
general (non-specific) reference uses the small caps form without underscore joining. A
direct reference example is: “The Supply_Group_Code is linked to a group of meters”,
while an indirect reference example is: “A supply group code links to a vending key”;
• other terms use the generally accepted abbreviated forms like PSTN for Public Switched
Telephone Network.
– 14 – TR 62055-21  IEC:2005(E)
4 General concepts
Processes
Make use of Make use of
Operate
on
Data elements Functions
Are embodied in Are embodied in
System entities
Are comprised of Are comprised of
Interact across
Interfaces
Users Devices
Instances Instance Instance
Supplier
Token Payment
carrier meter
Customer
Operator
interact across
Interfaces
Installer
Inspector
Meter reader
NOTE With outsourced services or deregulated market environments, there may be additional user instances
such as vending agents and retail network services providers.
Figure 1 – General concepts of a Payment Metering System
A Payment Metering System is a collective infrastructure that supports the contractual
relationship between a supplier of goods or services and a customer. It includes processes,
functions, data elements, system entities (devices and users) and interfaces.
A Process is a logically linked sequence of tasks and activities that enable the system to
achieve particular objectives in terms of the purpose for which it is designed. A process calls
on the services of functions, which in turn operate on data elements. A process may also
interact with other processes, (e.g. being invoked or terminated by another process) or it may
invoke several functions to achieve a particular result. Because a particular function may be
used by more than one process, there may be many more processes in a system than there
are functions. See also Clause 10 for more on generic processes.
A Function is the encapsulation of a defined capability or functionality of the system,
abstracted from the application domain, that gives the system entities the ability to act, react
and interact. The internal working of a function is itself a process, but this is invisible from an
external perspective, which sees only a start and end state. A process may thus also be
encapsulated into a single function. A function is always embodied in one or more of the
system entities and may even require several entities in order to realize a particular function.
It is a well-defined task with a start and end state that, when invoked, will cause the task to be
executed until completion. The end result of a function may be anything from a simple data
manipulation, through calculating the answer of a complex mathematical problem, to the
displaying of the contents of a particular register. It is important to note that a given function
may not necessarily be implemented in the same physical part or system entity of a particular
system as compared to that of another system even if the functions are identical. See also
Clause 11 for more on generic functions.

TR 62055-21  IEC:2005(E) – 15 –
Data Elements embody information about the properties or status of the system. They are the
most basic part of the system and should not be decomposed below this definition. Data
elements may vary from being the contents of a software register to being a visible marking
on a label of a meter panel indicating a meter serial number. Data elements are created,
recorded, transformed and moved around within the system by means of processes and
functions. See also Clause 12 for more on data elements.
System Entities are discrete devices and users of the system that are deployed and
configured within a system architecture in such a way as to enable the system to perform it’s
objectives. Devices are typically computers, modems, networks, printers, token carriers,
meters, software programs, etc. Each of these entities embodies functions and data elements
that participate in processes. Similarly users are typically customers, POS operators,
installation and maintenance personnel, etc. See also Clause 13 for more on system entities.
Interfaces will exist between those system entities that need to exchange data elements.
These interfaces will have data elements passing over them in support of the functions and
processes. Interfaces are selected at appropriate places within a defined architecture to suit a
clear objective of the system design. See also Clause 13 for more on interfaces.
5 The generic entity model
A generic entity model for electricity payment metering systems is shown in Figure 2.
Although it provides a limited perspective, it does serve to convey certain essential concepts.
Customer journeys
Token_Carrier
(physical)
Point_Of _Sale
ID
Alternatives
(virtual Token_Carrier)
Customer_
Payment_
Information_
Meter
Remote_Comms_Service
System
Meter_Operation
System_Users
Figure 2 – Generic entity model for electricity payment metering systems
The essential entities of a payment metering system are:
• the Payment_Meter;
• the Token_Carrier or Remote_Communication_Services p
...