IEC 61280-4-1:2019

IEC 61280-4-1 ®
Edition 3.1 2021-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre-optic communication subsystem test procedures –
Part 4-1: Installed cabling plant – Multimode attenuation measurement

Procédures d'essai des sous-systèmes de télécommunication fibroniques –
Partie 4-1: Installation câblée – Mesure de l’affaiblissement en multimodal

All rights reserved. Unless otherwise specified, 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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - IEC online collection - oc.iec.ch
webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez
La recherche avancée permet de trouver des publications IEC gratuitement tous les aperçus des publications. Avec un
en utilisant différents critères (numéro de référence, texte, abonnement, vous aurez toujours accès à un contenu à jour
comité d’études, …). Elle donne aussi des informations sur adapté à vos besoins.
les projets et les publications remplacées ou retirées.

Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
Le premier dictionnaire d'électrotechnologie en ligne au
Restez informé sur les nouvelles publications IEC. Just
monde, avec plus de 22 000 articles terminologiques en
Published détaille les nouvelles publications parues.
anglais et en français, ainsi que les termes équivalents dans
Disponible en ligne et une fois par mois par email.
16 langues additionnelles. Egalement appelé Vocabulaire

Electrotechnique International (IEV) en ligne.
Service Clients - webstore.iec.ch/csc

Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
IEC 61280-4-1 ®
Edition 3.1 2021-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre-optic communication subsystem test procedures –
Part 4-1: Installed cabling plant – Multimode attenuation measurement
Procédures d'essai des sous-systèmes de télécommunication fibroniques –
Partie 4-1: Installation câblée – Mesure de l’affaiblissement en multimodal
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-4941-3

IEC 61280-4-1 ®
Edition 3.1 2021-12
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Fibre-optic communication subsystem test procedures –
Part 4-1: Installed cabling plant – Multimode attenuation measurement

Procédures d'essai des sous-systèmes de télécommunication fibroniques –
Partie 4-1: Installation câblée – Mesure de l’affaiblissement en multimodal

– 2 – IEC 61280-4-1:2019+AMD1:2021 CSV
© IEC 2021
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, graphical symbols and abbreviated terms. 9
3.1 Terms and definitions . 10
3.2 Graphical symbols . 12
3.3 Abbreviated terms . 14
4 Test methods . 14
4.1 General . 14
4.2 Cabling configurations and applicable test methods . 15
5 Overview of uncertainties . 17
5.1 General . 17
5.2 Sources of significant uncertainties . 17
5.3 Consideration of the PM . 18
5.4 Consideration of test cord connector grade . 18
5.5 Typical uncertainty values . 18
6 Apparatus . 19
6.1 General . 19
6.2 Light source . 19
6.2.1 Stability . 19
6.2.2 Spectral characteristics (LSPM measurement) . 19
6.3 Launch cord . 20
6.4 Receive or tail cord . 20
6.5 Substitution cord . 21
6.6 Power meter – LSPM methods only. 21
6.7 OTDR apparatus . 21
6.8 Connector end face cleaning and inspection equipment . 22
6.9 Adapters . 22
7 Procedures . 22
7.1 General . 22
7.2 Common procedures . 23
7.2.1 Care of the test cords . 23
7.2.2 Make reference measurements (LSPM methods only). 23
7.2.3 Inspect and clean the ends of the optical fibres in the cabling . 23
7.2.4 Make the measurements . 23
7.2.5 Make the calculations . 23
7.2.6 Duplex and bi-directional testing . 23
7.3 Calibration . 23
7.4 Safety . 24
8 Calculations . 24
9 Documentation . 24
9.1 Information for each test . 24
9.2 Information to be available . 24
Annex A (normative) One-cord method . 25
A.1 Applicability of test method . 25

© IEC 2021
A.2 Apparatus . 25
A.3 Procedure . 25
A.4 Calculation . 26
A.5 Components of reported attenuation . 26
Annex B (normative) Three-cord method . 27
B.1 Applicability of test method . 27
B.2 Apparatus . 27
B.3 Procedure . 27
B.4 Calculations . 28
B.5 Components of reported attenuation . 28
Annex C (normative) Two-cord method . 29
C.1 Applicability of test method . 29
C.2 Apparatus . 29
C.3 Procedure . 29
C.4 Calculations . 30
C.5 Components of reported attenuation . 30
Annex D (normative) Equipment cord method . 32
D.1 Applicability of the test method . 32
D.2 Apparatus . 32
D.3 Procedure . 32
D.4 Calculation . 33
D.5 Components of reported attenuation . 33
D.6 Typical uncertainty values . 34
Annex E (normative) Optical time domain reflectometer . 35
E.1 Applicability of the test method . 35
E.2 Apparatus . 35
E.2.1 General . 35
E.2.2 OTDR . 35
E.2.3 Test cords . 35
E.3 Procedure (test method) . 36
E.4 Calculation . 37
E.4.1 General . 37
E.4.2 Connection location . 37
E.4.3 Definition of power levels F and F . 38
1 2
E.4.4 Alternative calculation. 38
E.5 OTDR uncertainties . 40
Annex F (normative) Requirements for the source characteristics . 42
F.1 Encircled flux . 42
F.2 Assumptions and limitations . 42
F.3 Encircled flux templates . 42
F.3.1 General . 42
F.3.2 Uncertainties expectations . 43
F.3.3 Templates. 43
F.4 Graphical representation of templates . 44
Annex G (informative) OTDR configuration information . 46
G.1 General . 46
G.2 Fundamental parameters that define the operational capability of an OTDR . 47
G.2.1 Dynamic range . 47

– 4 – IEC 61280-4-1:2019+AMD1:2021 CSV
© IEC 2021
G.2.2 Pulse width . 47
G.2.3 Averaging time . 47
G.2.4 Dead zone . 47
G.3 Other parameters . 47
G.3.1 Index of refraction . 47
G.3.2 Measurement range . 48
G.3.3 Distance sampling . 48
G.4 Other measurement configurations . 48
G.4.1 General . 48
G.4.2 Macrobend or splice attenuation measurement . 48
G.4.3 Splice attenuation measurement . 49
G.4.4 Measurement with high reflection connectors or short length cabling . 49
G.4.5 Ghost . 51
G.5 More on the measurement method . 52
G.6 Bi-directional measurement . 53
G.7 Non-recommended practices. 54
G.7.1 Measurement without tail test cord . 54
G.7.2 Cursor measurement . 54
Annex H (informative) Test cord attenuation verification . 55
H.1 General . 55
H.2 Apparatus . 55
H.3 Procedure . 55
H.3.1 General . 55
H.3.2 Test cord verification for the one-cord and two-cord methods when
using non-pinned/unpinned and non-plug/socket style connectors . 56
H.3.3 Test cord verification for the one-cord and two-cord methods when
using pinned/unpinned or plug/socket style connectors . 57
H.3.4 Test cord verification for the three-cord method when using non-
pinned/unpinned and non-plug/socket style connectors . 59
H.3.5 Test cord verification for the three-cord method when using
pinned/unpinned or plug/socket style connectors . 61
Annex I (normative) On the use of reference-grade test cords. 63
I.1 General . 63
I.2 Practical configurations and assumptions. 63
I.2.1 Component specifications . 63
I.2.2 Conventions . 64
I.2.3 Reference planes . 64
I.3 Impact of using reference grade test cords for recommended LSPM methods . 64
I.4 Examples for LSPM measurements . 65
I.4.1 Example 1 (configuration A, 1-C method – Annex A) . 65
I.4.2 Example 2 (configuration D, EC method – Annex D) . 65
I.5 Impact of using reference-grade test cords for different configurations using
the OTDR test method . 66
I.5.1 Cabling configurations A, B and C . 66
I.5.2 Cabling configuration D . 67
Annex J (informative) Launch cord output near-field verification. 69
J.1 Direct verification . 69
J.2 Test equipment manufacturer verification . 69
J.3 Field check with physical artefact . 69
J.3.1 General . 69

© IEC 2021
J.3.2 Procedure for attenuation characterization of artefacts . 71
J.3.3 Construction details . 71
J.3.4 Example results . 72
Bibliography . 76

Figure 1 – Connector symbols . 13
Figure 2 – Symbol for cabling under test . 13
Figure 3 – Reference plane for configuration A tested with the 1-cord method . 16
Figure 4 – Reference plane for configuration B tested with the 3-cord method . 16
Figure 5 – Reference plane for configuration C tested with the 2-cord method . 17
Figure 6 – Reference plane for configuration D tested with the EC method . 17
Figure 7 – OTDR schematic . 22
Figure A.1 – Reference measurement . 26
Figure A.2 – Test measurement . 26
Figure B.1 – Reference measurement . 27
Figure B.2 – Test measurement . 28
Figure C.1 – Reference measurement . 29
Figure C.2 – Test measurement . 30
Figure C.3 – Test measurement for plug-socket style connectors . 30
Figure D.1 – Reference measurement . 33
Figure D.2 – Test measurement . 33
Figure E.1 – OTDR method . 36
Figure E.2 – Location of the ports of the cabling under test . 37
Figure E.3 – Graphic construction of F and F . 38
1 2
Figure E.4 – Graphic construction of F , F , F and F . 40
1 11 12 2
Figure F.1 – Encircled flux example . 45
Figure G.1 – Splice and macrobend attenuation measurement . 49
Figure G.2 – Attenuation measurement with high reflection connectors . 50
Figure G.3 – Attenuation measurement of a short length cabling. 51
Figure G.4 – OTDR trace with ghost . 52
Figure G.5 – Cursor positioning . 53
Figure H.1 – Obtaining reference power level P . 57
Figure H.2 – Obtaining power level P . 57
Figure H.3 – Obtaining reference power level P . 58
Figure H.4 – Obtaining power level P . 58
Figure H.5 – Obtaining reference power level P . 59
Figure H.6 – Obtaining power level . 59
Figure H.7 – Obtaining reference power level P . 60
Figure H.8 – Obtaining power level P . 60
Figure H.9 – Obtaining power level P . 61
Figure H.10 – Obtaining reference power level P . 62
– 6 – IEC 61280-4-1:2019+AMD1:2021 CSV
© IEC 2021
Figure H.11 – Obtaining power level P . 62
Figure I.1 – Cabling configurations A, B and C tested with the OTDR method . 66
Figure I.2 – Cabling configuration D tested with the OTDR method . 68
Figure J.1 – Initial power measurement . 70
Figure J.2 – Verification of reference-grade connection . 70
Figure J.3 – Two offset splices . 70
Figure J.4 – Five offset splices . 71
Figure J.5 – EF centred . 72
Figure J.6 – EF underfilling . 73
Figure J.7 – EF overfilling . 73
Figure J.8 – L1 attenuation with mandrel. 74
Figure J.9 – L1 attenuation with mandrel and mode conditioner . 74
Figure J.10 – L2 attenuation with mandrel . 74
Figure J.11 – L2 attenuation with mandrel and mode conditioning . 75
Figure J.12 – L3 attenuation with mandrel . 75
Figure J.13 – L3 attenuation with mandrel and mode conditioning . 75

Table 1 – Cabling configurations . 15
Table 2 – Test methods and configurations . 15
Table 3 – Measurements bias related to test cord connector grade . 18
Table 4 – Uncertainty for a given attenuation at 850 nm . 19
Table 5 – Spectral requirements . 19
Table D.1 – Uncertainty for a given attenuation at 850 nm . 34
Table F.1 – Attenuation, threshold tolerance and confidence level . 43
Table F.2 – EF requirements for 50 µm core optical fibre cabling at 850 nm . 43
Table F.3 – EF requirements for 50 μm core optical fibre cabling at 1 300 nm. 44
Table F.4 – EF requirements for 62,5 μm core optical fibre cabling at 850 nm. 44
Table F.5 – EF requirements for 62,5 μm core optical fibre cabling at 1 300 nm . 44
Table G.1 – Default effective group index of refraction values . 48
Table I.1 – Measurement bias when using reference-grade test cords . 65
Table I.2 – Measurement bias when using reference grade test cords – OTDR test
method . 67

© IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –
Part 4-1: Installed cabling plant – Multimode attenuation measurement
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
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.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 61280-4-1 edition 3.1 contains the third edition (2019-05) [documents 86C/1575/FDIS
and 86C/1592/RVD], its corrigenda 1 (2020-04) and 2 (2022-12), and its amendment 1
(2021-12) [documents 86C/1720/CDV and 86C/1592/RVD].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendment 1. Additions are in green text, deletions are in strikethrough red
text. A separate Final version with all changes accepted is available in this publication.

– 8 – IEC 61280-4-1:2019+AMD1:2021 CSV
© IEC 2021
International Standard IEC 61280-4-1 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86: Fibre optics.
This third edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) changes to Annex F on encircled flux to harmonise with IEC TR 62614-2, but keeping the
encircled flux limits defined in Tables F.2 to F.5 unchanged;
b) addition of an equipment cord method in Annex D;
c) inclusion of testing bend insensitive multimode optical fibre;
d) updates to measurement uncertainty;
e) definition of additional cabling configurations;
f) changes to Table 5 on spectral requirements.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61280 series, published under the general title Fibre optic
communication subsystem test procedures, can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendment will
remain unchanged until the stability date indicated on the IEC web site under 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

© IEC 2021
FIBRE-OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –

Part 4-1: Installed cabling plant – Multimode attenuation measurement

1 Scope
This part of IEC 61280 is applicable to the measurement of attenuation of installed optical fibre
cabling plant using multimode optical fibre. This cabling plant can include multimode optical
fibres, connectors, adapters, splices, and other passive devices. The cabling can be installed
in a variety of environments including residential, commercial, industrial, and data centre
premises, as well as outside plant environments. The test equipment used in this document has
one single fibre connector interface or two single fibre connector interfaces.
In this document, the optical fibres that are addressed include sub-categories A1-OMx, where
x = 2, 3, 4 and 5 (50/125 μm) and A1-OM1 (62,5/125 μm) multimode optical fibres, as specified
in IEC 60793-2-10. The attenuation measurements of the other multimode categories can be
made using the approaches of this document, but the source conditions for the other categories
have not been defined.
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.
IEC 60825-2, Safety of laser products – Part 2: Safety of optical fibre communication systems
(OFCS)
IEC 61280-1-3, Fibre optic communication subsystem test procedures – Part 1-3: General
communication subsystems – Central wavelength and spectral width measurement
IEC 61280-1-4, Fibre optic communication subsystem test procedures – Part 1-4: General
communication subsystems – Light source encircled flux measurement method
IEC 61300-3-35, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-35: Examinations and measurements – Visual inspection of
fibre optic connectors and fibre-stub transceivers
IEC 61315, Calibration of fibre-optic power meters
IEC 61746-2, Calibration of optical time-domain reflectometers (OTDR) – Part 2: OTDR for
multimode fibres
3 Terms, definitions, graphical symbols and abbreviated terms
For the purposes of this document, the following terms, definitions, graphical symbols and
abbreviated terms apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– 10 – IEC 61280-4-1:2019+AMD1:2021 CSV
© IEC 2021
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
attenuation
A
reduction of optical power induced by transmission through a medium such as cabling
A = 10 log(P /P )
in out
where
and P are the power, typically measured in mW, into and out of the cabling
P
in out
Note 1 to entry: Attenuation is expressed in dB.
3.1.2
light source power meter
LSPM
test system consisting of a light source (LS) and power meter (PM) used to measure the
attenuation of installed cabling plant
3.1.3
optical time domain reflectometer
OTDR
test system consisting of an optical time-domain reflectometer instrument used to characterize
and measure the attenuation of installed cabling plant and specific elements within that cabling
plant
Note 1 to entry: This note applies to the French language only.
3.1.4
test cord
terminated optical fibre cord used to connect the optical source or detector to the cabling, or to
provide suitable interfaces to the cabling under test
Note 1 to entry: There are five types of test cords:
– launch cord: used to connect the light source to the cabling;
– receive cord: used to connect the cabling to the power meter (LSPM only);
– tail cord: attached to the far end of the cabling when an OTDR is used at the near end. This provides a means
of evaluating attenuation of the whole of the cabling including the far end connection;
– adapter cord: used to transition between sockets or other incompatible connectors in a required test configuration;
– substitution cord: a test cord used within a reference measurement which is replaced during the measurement
of the attenuation of the cabling under test.
3.1.5
bi-directional measurement
two measurements of the same optical fibre, made by launching light into opposite ends of that
fibre
3.1.6
configuration
form or arrangements of parts or elements such as terminations, connections and splices

© IEC 2021
3.1.7
encircled flux
EF
fraction of cumulative near-field power to the total output power as a function of radial distance
from the optical centre of the core
[SOURCE: IEC 62614:2010, 3.2]
3.1.8
reference-grade termination
connector and plug with tightened tolerances terminated onto an optical fibre with tightened
tolerances such that the expected attenuation of a connection formed by mating two such
assemblies is lower and more repeatable than a standard-grade termination
Note 1 to entry: An adapter, required to assure the reduced attenuation, may be considered as part of the
reference-grade termination where required by the test configuration.
Note 2 to entry: IEC 61755-6-2 defines reference-grade terminations for 50/125 µm fibre.
3.1.9
connector
component normally attached to an optical cable or piece of apparatus for the purpose of
providing frequent optical interconnection/disconnection of optical fibres or cables
[SOURCE: IEC TR 61931:1998, 2.6.1, modified – The words in brackets, "optical" and "fibre",
have been omitted from the term.]
3.1.10
plug
male-type part of a connector
[SOURCE: IEC TR 61931:1998, 2.6.2]
3.1.11
adapter
female-type part of a connector in which one or two plugs are inserted and aligned
[SOURCE: IEC TR 61931:1998, 2.6.4]
3.1.12
socket-style connector
connector for which the adapter, including any alignment device, is integrated with and
permanently attached to the connector plug on one side of the connection
Note 1 to entry: Examples include many harsh environment connectors.
3.1.13
reference test method
RTM
test method for measuring a given characteristic strictly according to the definition of this
characteristic, and giving results which are accurate, reproducible and relatable to practical use
Note 1 to entry: This note applies to the French language only.
[SOURCE: IEC
...