IEC 61784-3-3:2007

IEC 61784-3-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Profiles –
Part 3-3: Functional safety fieldbuses – Additional specifications for CPF 3

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IEC 61784-3-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Profiles –
Part 3-3: Functional safety fieldbuses – Additional specifications for CPF 3

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XE
ICS 35.100.20 25.040.40 ISBN 2-8318-9400-X

– 2 – 61784-3-3 © IEC:2007(E)
CONTENTS
FOREWORD.8

INTRODUCTION.10

1 Scope.13

2 Normative references .13

3 Terms, definitions, symbols, abbreviated terms and conventions .15

3.1 Terms and definitions .15

3.1.1 Common terms and definitions .15

3.1.2 CPF 3: Additional terms and definitions .19
3.2 Symbols and abbreviated terms.23
3.2.1 Common symbols and abbreviated terms .23
3.2.2 CPF 3: Additional symbols and abbreviated terms .23
3.3 Conventions .24
4 Overview of FSCP 3/1 (PROFIsafe™) .25
5 General .27
5.1 External documents providing specifications for the profile.27
5.2 Safety functional requirements .27
5.3 Safety measures .28
5.4 Safety communication layer structure .29
5.4.1 Principle of FSCP 3/1 safety communications .29
5.4.2 CPF 3 communication structures .30
5.5 Relationships with FAL (and DLL, PhL) .33
5.5.1 Device model.33
5.5.2 Application and communication relationships.33
5.5.3 Message format.35
5.5.4 Data types .35
6 Safety communication layer services .36
6.1 F-Host services .36
6.2 F-Device services.39
6.3 Diagnosis .40
6.3.1 Safety alarm generation.40
6.3.2 F-Device safety layer diagnosis including the iPar-Server.40
7 Safety communication layer protocol .41

7.1 Safety PDU format .41
7.1.1 Safety PDU structure.41
7.1.2 Safety I/O data .42
7.1.3 Status and Control Byte.42
7.1.4 (Virtual) Consecutive Number.44
7.1.5 CRC2 Signature .45
7.1.6 Appended standard I/O data .46
7.2 FSCP 3/1 behavior .46
7.2.1 General .46
7.2.2 F-Host state diagram .47
7.2.3 F-Device state diagram.50
7.2.4 Sequence diagrams.54
7.2.5 Timing diagram for a counter reset .60
7.2.6 Monitoring of safety times.60

61784-3-3 © IEC:2007(E) – 3 –
7.3 Reaction in the event of a malfunction.63

7.3.1 Repetition.63

7.3.2 Loss .63

7.3.3 Insertion .63

7.3.4 Incorrect sequence .63

7.3.5 Corruption of safety data .63

7.3.6 Delay.64

7.3.7 Masquerade .64

7.3.8 Memory failures within switches .65

7.3.9 Network boundaries and router.66

7.4 F-Startup and change coordination.66
7.4.1 Standard startup procedure .66
7.4.2 iParameter assignment deblocking .66
8 Safety communication layer management.67
8.1 F-Parameter .67
8.1.1 Summary.67
8.1.2 F_Source/Destination_Address (codename) .67
8.1.3 F_WD_Time (F-Watchdog time).68
8.1.4 F_Prm_Flag1 (Parameters for the safety layer management) .68
8.1.5 F_Prm_Flag2 (Parameters for the safety layer management) .69
8.1.6 F_iPar_CRC (value of iPar_CRC across iParameters) .70
8.1.7 F_Par_CRC (CRC1 across F-Parameters) .71
8.1.8 Structure of the F-Parameter record data object .71
8.1.9 F-Data fraction .71
8.2 iParameter and iPar_CRC .72
8.3 Safety parameterization.73
8.3.1 Objectives .73
8.3.2 GSD and GSDML safety extensions .73
8.3.3 Securing safety parameters and GSD data .74
8.4 Safety configuration .76
8.4.1 Securing the safety I/O data description (CRC7).76
8.4.2 DataItem data type section examples .77
8.5 Data type information usage.79
8.5.1 F-Channel driver.79
8.5.2 Rules for standard F-Channel drivers .80

8.5.3 Recommendations for F-Channel drivers .80
8.6 Safety parameter assignment mechanisms.81
8.6.1 F-Parameter assignment .81
8.6.2 General iParameter assignment.82
8.6.3 System integration requirements for iParameterization tools.83
8.6.4 iPar-Server .84
9 System requirements.92
9.1 Indicators and switches .92
9.2 Installation guidelines.93
9.3 Safety function response time .93
9.3.1 Model .93
9.3.2 Calculation and optimization.95
9.3.3 Adjustment of watchdog times for FSCP 3/1 .96
9.3.4 Engineering tool support.97

– 4 – 61784-3-3 © IEC:2007(E)
9.3.5 Retries (repetition of messages) .97

9.4 Duration of demands .98

9.5 Constraints for the calculation of system characteristics.99

9.5.1 Probabilistic considerations .99

9.5.2 Safety related constraints .101

9.5.3 Non safety related constraints (availability).102

9.6 Maintenance.102

9.6.1 F-Module commissioning / replacement .102

9.6.2 Identification and maintenance functions . 102

9.7 Safety manual .103

9.8 Wireless transmission channels.103
9.8.1 Black Channel approach.103
9.8.2 Availability.104
9.8.3 Security measures.104
9.8.4 Stationary and mobile applications . 106
9.9 Conformance classes .106
10 Certification.107
10.1 Safety policy .107
10.2 Obligations .108
Annex A (informative) Additional information for functional safety communication
profiles of CPF 3 .109
A.1 Hash function calculation.109
A.2 Response time measurements.111
Bibliography.115

Table 1 – Deployed measures to master errors .28
Table 2 – Data types used for FSCP 3/1 .35
Table 3 – Safety layer diagnosis messages .40
Table 4 – F-Host states and transitions.48
Table 5 – F-Device states and transitions .52
Table 6 – SIL monitor times .63
Table 7 – Remedies for switch failures.65
Table 8 – Safety network boundaries .66

Table 9 – I/O data structure items (Version 2).76
Table 10 – Sample F-Channel drivers .80
Table 11 – Requirements for iParameterization.83
Table 12 – Specifier for the iPar-Server Request .87
Table 13 – Structure of the Read_RES_PDU ("read record").88
Table 14 – Structure of the Write_REQ_PDU ("write record").89
Table 15 – Structure of the Pull_RES_PDU ("Pull").89
Table 16 – Structure of the Push_REQ_PDU ("Push") .89
Table 17 – iPar-Server states and transitions.91
Table 18 – iPar-Server management measures.92
Table 19 – Information to be included in the safety manual. 103
Table 20 – Security measures for WLAN (IEEE 802.11i) . 105

61784-3-3 © IEC:2007(E) – 5 –
Table 21 – Security measures for Bluetooth (IEEE 802.15.1) . 106

Table 22 – F-Host conformance class requirements. 107

Table A.1 – The table "Crctab24" for 24 bit CRC signature calculations . 110

Table A.2 – The table "Crctab32" for 32 bit CRC signature calculations . 111

Figure 1 – Relationships of IEC 61784-3 with other standards (machinery) .10

Figure 2 – Relationships of IEC 61784-3 with other standards (process).11

Figure 3 – Basic communication preconditions for FSCP 3/1 .25

Figure 4 – Structure of an FSCP 3/1 safety PDU.26
Figure 5 – Safe communication modes .27
Figure 6 – Standard CPF 3 transmission system.29
Figure 7 – Safety layer architecture .30
Figure 8 – Basic communication layers .30
Figure 9 – Multiport switch bus structure.31
Figure 10 – Linear bus structure .31
Figure 11 – Crossing network borders with routers .32
Figure 12 – Complete safety transmission paths .32
Figure 13 – Device model .33
Figure 14 – Application relationships of a modular device .34
Figure 15 – Application and communication relationships (AR/CR) .34
Figure 16 – Message format .35
Figure 17 – FSCP 3/1 communication structure .37
Figure 18 – F user interface of F-Host driver instances .37
Figure 19 – F-Device driver interfaces .39
Figure 20 – Safety PDU for CPF 3 .42
Figure 21 – Status Byte .42
Figure 22 – Control Byte .43
Figure 23 – The Toggle Bit function .44
Figure 24 – F-Device Consecutive Number .44
Figure 25 – CRC2 generation (F-Host output) .45

Figure 26 – Details of the CRC2 calculation (reverse order).46
Figure 27 – Safety layer communication relationship.46
Figure 28 – F-Host state diagram.47
Figure 29 – F-Device state diagram .51
Figure 30 – Interaction F-Host / F-Device during start-up.54
Figure 31 – Interaction F-Host / F-Device during F-Host power off → on.55
Figure 32 – Interaction F-Host / F-Device with delayed power on.56
Figure 33 – Interaction F-Host / F-Device during power off → on .57
Figure 34 – Interaction F-Host / F-Device while host recognizes CRC error .58
Figure 35 – Interaction F-Host / F-Device while device recognizes CRC error .59
Figure 36 – Impact of the counter reset signal .60
Figure 37 – Monitoring the message transit time F-Host ↔ F-Output .61

– 6 – 61784-3-3 © IEC:2007(E)
Figure 38 – Monitoring the message transit time F-Input ↔ F-Host .61

Figure 39 – F-Parameter data and CRC .64

Figure 40 – iParameter assignment deblocking by the F-Host .67

Figure 41 – F_Prm_Flag1 .68

Figure 42 – F_Check_SeqNr.68

Figure 43 – F_Check_iPar .69

Figure 44 – F_SIL .69

Figure 45 – F_CRC_Length .69

Figure 46 – F_Prm_Flag2 .70
Figure 47 – F_Block_ID .70
Figure 48 – F_Par_Version .70
Figure 49 – F-Parameter.71
Figure 50 – iParameter block .72
Figure 51 – F-Parameter extension within the GSDML specification.74
Figure 52 – CRC1 including iPar_CRC.75
Figure 53 – Algorithm to build CRC0.75
Figure 54 – DataItem section for F_IN_OUT_1.77
Figure 55 – DataItem section for F_IN_OUT_2.78
Figure 56 – DataItem section for F_IN_OUT_5.78
Figure 57 – DataItem section for F_IN_OUT_6.79
Figure 58 – F-Channel driver as "glue" between F-Device and user program .79
Figure 59 – Layout example of an F-Channel driver .80
Figure 60 – F-Parameter assignment for simple F-Devices and F-Slaves.81
Figure 61 – F and iParameter assignment for complex F-Devices .82
Figure 62 – System integration of CPD-Tools.84
Figure 63 – iPar-Server mechanism (commissioning).84
Figure 64 – iPar-Server mechanism (for example F-Device replacement) .85
Figure 65 – iPar-Server request coding ("status model") .86
Figure 66 – Coding of SR_Type .87
Figure 67 – iPar-Server request coding ("alarm model").88
Figure 68 – iPar-Server state diagram .90

Figure 69 – Example safety function with a critical response time path .93
Figure 70 – Simplified typical response time model.94
Figure 71 – Frequency distributions of typical response times of the model .94
Figure 72 – Context of delay times and watchdog times.95
Figure 73 – Timing sections forming the FSCP 3/1 F_WD_Time .96
Figure 74 – Frequency distribution of response times with message retries .97
Figure 75 – Retries with CP 3/1 .98
Figure 76 – Retries with CP 3/RTE .98
Figure 77 – Residual error probabilities for the 24-bit polynomial .99
Figure 78 – Properness of the 32-bit polynomial for 52 octets .100
Figure 79 – Properness of the 32-bit polynomial for 132 octets .100
Figure 80 – Monitoring of corrupted messages.101

61784-3-3 © IEC:2007(E) – 7 –
Figure 81 – Security for WLAN networks.104

Figure 82 – Security for Bluetooth networks.105

Figure A.83 – Typical "C" procedure of a cyclic redundancy check. 109

Figure A.84 – Comparison of the response time model and a real application . 112

Figure A.85 – Frequency distribution of measured response times. 113

Figure A.86 – F-Host with standard and safety-related application programs . 114

– 8 – 61784-3-3 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
INDUSTRIAL COMMUNICATION NETWORKS – PROFILES

Part 3-3: Functional safety fieldbuses – Additional specifications

for CPF 3
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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that compliance
with this document may involve the use of patents concerning the functional safety communication profiles for

family 3 as follows, where the [xx] notation indicates the holder of the patent right:
EP1267270-A2 [SI] Verfahren zur Datenübertragung in einem
Rechnersystem
WO00/045562-A1 [SI] Method and device for determining the reliability of data
carriers
WO99/049373-A1 [SI] Shortened data message of an automation system
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patents rights have assured the IEC that they are willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the
statement of the holders of these patent rights are registered with IEC.
Information may be obtained from:
[SI] Siemens AG
A&D AS FA TC
Karlsruhe
Germany
61784-3-3 © IEC:2007(E) – 9 –
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights

other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61784-3-3 has been prepared by subcommittee 65C: Industrial

networks, of IEC technical committee 65: Industrial process measurement, control and

automation.
The text of this standard is based on the following documents:

FDIS Report on voting
65C/470/FDIS 65C/481/RVD
Full information on the voting for the approval of this standard 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.
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.
The list of all parts of the IEC 61784-3 series, under the general title Industrial communication
networks – Profiles – Functional safety fieldbuses, can be found on the IEC website.

– 10 – 61784-3-3 © IEC:2007(E)

INTRODUCTION
The IEC 61158 fieldbus standard together with its companion standards IEC 61784-1 and

IEC 61784-2 defines a set of communication protocols that enable distributed control of

automation applications. Fieldbus technology is now considered well accepted and well

proven. Thus many fieldbus enhancements are emerging, addressing not yet standardized

areas such as real time, safety-related and security-related applications.

This standard explains the relevant principles for functional safety communications with

reference to IEC 61508 series and specifies several safety communication layers (profiles and

corresponding protocols) based on the communication profiles and protocol layers of

IEC 61784-1, IEC 61784-2 and the IEC 61158 series. It does not cover electrical safety and
intrinsic safety aspects.
Figure 1 shows the relationships between this standard and relevant safety and fieldbus
standards in a machinery environment.
Product standards
ISO 12100-1 and ISO 14121
ISO 12100-1 and ISO 14121
IEC 61496 IEC 61131-6 IEC 61800-5-2 Safety of machinery – Principles for
IEC 61496 IEC 61131-6 IEC 61800-5-2 Safety of machinery – Principles for
Safety f. e.g. Safety for Safety functions design and risk assessment
Safety for PLC design and risk assessment
Safety f. e.g. Safety for Safety functions
light curtains PLC for drives
(under consideration)
light curtains PLC for drives
Design of safety-related electrical, electronic and programmable
IEC 61784-4 IEC 62443
IEC 61784-4 IEC 62443
electronic control systems (SRECS) for machinery
Security Security
Security Security
(profile-specific) (common part)
(profile-specific) (common part)
SIL based PL based
IEC 61784-5 IEC 61918
IEC 61784-5 IEC 61918
Design objective
Installation guide Installation guide
Installation guide Installation guide
(profile-specific) (common part) Applicable standards
(profile-specific) (common part)
ISO 13849-1, -2
ISO 13849-1, -2
IEC 60204-1
IEC 60204-1
Safety-related parts
Safety-related parts
Safety of electrical
Safety of electrical
IEC 61326-3-1
of machinery
IEC 61326-3-1 of machinery
equipment
equipment
EMC and (SRPCS)
EMC and (SRPCS)
functional safety
functional safety
IEC 61784-3
IEC 61784-3
Non-electrical
Non-electrical
Functional safety
Functional safety
communication
communication
Electrical
Electrical
US: NFPA 79
US: NFPA 79
profiles
profiles
(2006)
(2006)
IEC 62061
IEC 62061
Functional safety
Functional safety
IEC 61158 series /
IEC 61158 series /
for machinery
for machinery
IEC 61508 series
IEC 61784-1, -2
IEC 61784-1, -2 IEC 61508 series (SRECS)
(SRECS)
Functional safety
Fieldbus for use in Functional safety (including EMI for
Fieldbus for use in (including EMI for
(basic standard)
(basic standard) industrial environment)
industrial control systems industrial environment)
industrial control systems
Key
(yellow) safety-related standards
(blue) fieldbus-related standards
(dashed yellow) this standard
Figure 1 – Relationships of IEC 61784-3 with other standards (machinery)

61784-3-3 © IEC:2007(E) – 11 –

Figure 2 shows the relationships between this standard and relevant safety and fieldbus

standards in a process environment.

Product standards
IEC 61496 IEC 61131-6 IEC 61800-5-2
IEC 61496 IEC 61131-6 IEC 61800-5-2

Safety f. e.g. SaSfetafye fotyr foPLrC Safety functions
Safety f. e.g. Safety for Safety functions
(under consideration)
light curtains PLC for drives
light curtains PLC for drives
IEC 61784-4 IEC 62443
IEC 61784-4 IEC 62443
Security Security
Security Security
(profile-specific) (common part)
(profile-specific) (common part)

See safety standards for machinery
(Figure 1)
IEC 61784-5 IEC 61918
IEC 61784-5 IEC 61918
Installation guide Installation guide
Installation guide Installation guide
(profile-specific) (common part)
(profile-specific) (common part)
Valid also in process industries,
whenever applicable
a)
a)
IEC 61326-3-2
IEC 61326-3-2
EMC and
EMC and
functional safety
functional safety
IEC 61784-3
IEC 61784-3
Functional safety
Functional safety
communication
communication
profiles
profiles
US:
US:
ISA-84.00.01
ISA-84.00.01
b)
b)
IEC 61511 series (3 parts = modified
IEC 61511 series (3 parts = modified
Functional safety – IEC 61511)
IEC 61158 series / Functional safety – IEC 61511)
IEC 61158 series /
Safety instrumented
Safety instrumented
IEC 61784-1, -2 IEC 61508 series
IEC 61784-1, -2 IEC 61508 series
systems for the
systems for the
Functional safety
Fieldbus for use in
Functional safety
Fieldbus for use in DE: VDI 2180
DE: VDI 2180
process industry sector
process industry sector
(basic standard)
(basic standard)
industrial control systems Part 1-4
industrial control systems
Part 1-4
Key
(yellow) safety-related standards
(blue) fieldbus-related standards
(dashed yellow) this standard
a
For specified electromagnetic environments; otherwise IEC 61326-3-1.
b
EN ratified.
Figure 2 – Relationships of IEC 61784-3 with other standards (process)

Safety communication layers which are implemented as parts of safety-related systems
according to IEC 61508 series provide the necessary confidence in the transportation of
messages (information) between two or more participants on a fieldbus in a safety-related
system, or sufficient confidence of safe behaviour in the event of fieldbus errors or failures.
Safety communication layers specified in this standard do this in such a way that a fieldbus
can be used for applications requiring functional safety up to the Safety Integrity Level (SIL)
specified by its corresponding functional safety communication profile.
The resulting SIL claim of a system depends on the implementation of the selected functional
safety communication profile within this system – implementation of a functional safety
communication profile in a standard device is not sufficient to qualify it as a safety device.

– 12 – 61784-3-3 © IEC:2007(E)

This standard describes
⎯ basic principles for implementing the requirements of IEC 61508 series for safety-

related data communications, including possible transmission faults, remedial

measures and considerations affecting data integrity;

⎯ individual description of functional safety profiles for several communication profile

families in IEC 61784-1 and IEC 61784-2;

⎯ safety layer extensions to the communication service and protocols sections of the

IEC 61158 series.
61784-3-3 © IEC:2007(E) – 13 –

INDUSTRIAL COMMUNICATION NETWORKS – PROFILES

Part 3-3: Functional safety fieldbuses – Additional specifications

for CPF 3
1 Scope
This part of the IEC 61784-3 series specifies a safety communication layer (services and

protocol) based on CPF 3 of IEC 61784-1, IEC 61784-2 (CP 3/1, CP 3/2, CP 3/4, CP 3/5 and
CP 3/6) and IEC 61158 Types 3 and 10. It identifies the principles for functional safety
communications defined in IEC 61784-3 that are relevant for this safety communication layer.
NOTE 1 It does not cover electrical safety and intrinsic safety aspects. Electrical safety relates to hazards such
as electrical shock. Intrinsic safety relates to hazards associated with potentially explosive atmospheres.
This part defines mechanisms for the transmission of safety-relevant messages among
participants within a distributed network using fieldbus technology in accordance with the
requirements of IEC 61508 for functional safety. These mechanisms may be used in various
industrial applications such as process control, manufacturing automation and machinery.
This part provides guidelines for both developers and assessors of compliant devices and
systems.
NOTE 2 The resulting SIL claim of a system depends on the implementation of the selected functional safety
communication profile within this system – implementation of a functional safety communication profile according to
this part in a standard device is not sufficient to qualify it as a safety device.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 61010-1, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 1: General requirements
IEC 61131-2, Programmable controllers – Part 2: Equipment requirements and tests
IEC 61131-3, Programmable controllers – Part 3: Programming languages

IEC 61158 (all parts), Industrial communication networks – Fieldbus specifications
IEC 61158-2, Industrial communication networks – Fieldbus specifications – Part 2: Physical
layer specification and service definition
IEC 61158-3-3, Industrial communication networks – Fieldbus specifications – Part 3-3: Data-
link layer service definition
IEC 61158-4-3, Industrial communication networks – Fieldbus specifications – Part 4-3: Data-
link layer protocol specification
IEC 61158-5-3, Industrial communication networks – Fieldbus specifications – Part 5-3:
Application layer service definition
—————————
In the following pages of this standard, “this part
...