prEN IEC 60073:2026

• Status: Not Published
• Publication Date: 18-Jan-2028
• ICS: 01.070 - Colour coding
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: CLC/SR 3 - Information structures, documentation and graphical symbols
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 14-Aug-2026
• Due Date: 01-Oct-2025
• Completion Date: 14-Aug-2026
• Ref Project: oSIST prEN IEC 60073:2026 - Basic and safety principles for man-machine interface, marking and identification - Coding principles for indicators and actuators

• Revises: EN 60073:2002 - Basic and safety principles for man-machine interface, marking and identification - Coding principles for indicators and actuators
• Effective Date: 11-Jun-2024

prEN IEC 60073:2026 is an IEC basic safety publication on coding principles for indicators and HMI actuators in human-machine interfaces. It specifies how visual, acoustic and tactile signals are assigned meanings for monitoring, control, maintenance and rapid recognition of control conditions, with attention to safety of persons, property and the environment. The standard is intended for technical committees and for designers of equipment, processes and control stations that need a consistent signalling scheme.

What does prEN IEC 60073:2026 specify?

prEN IEC 60073:2026 establishes general rules for assigning meanings to signals, from a single indicator light or push-button to large control stations. It is organized into Scope, Normative references, Terms and definitions, Coding principles, and Application requirements, followed by three annexes.

Annex	What it covers
Annex A	Special requirements for mechanical indicators
Annex B	Example for applying indication coding using colours
Annex C	Examples of visual, acoustic and tactile signals

The scope covers general application where signals are used to improve safety, help monitoring and maintenance, and make control conditions easier to recognize. It also states that the standard is a Basic safety publication for use by technical committees when preparing safety publications.

What are the key requirements of prEN IEC 60073:2026?

General coding rules

prEN IEC 60073:2026 says coding principles should be set early in system design and kept consistent within the same plant or process. The chosen code must match the task to be performed and the operating conditions, and its meaning must be clear in the equipment, process or plant documentation.

In practice, this means a site should not invent ad hoc colours or signals at each machine. The same meaning should be used wherever operators have to interpret the same type of status or warning.

Visual signals

prEN IEC 60073:2026 treats colour and flashing as the most effective visual means, but colour must not be the only coding method. If colour carries a safety meaning, the document calls for supplementary coding, and if colour is the sole means it must remain within the chromaticity boundary defined in ISO 3864-4 during the expected life and operating conditions.

The standard assigns meanings to RED, YELLOW, GREEN, BLUE, WHITE, GREY and BLACK for indicators and HMI actuators. It uses those colours differently for safety of persons or the environment, for process condition, and for equipment state, so the reader must choose the table that matches the application.

Shapes, position and time-based coding

prEN IEC 60073:2026 allows shapes, position, or both, as a main code or as a supplementary code. Shapes used for safety-related applications are to be bold-rimmed, while shapes used for process or equipment state are not. Position coding is mainly for the state of a process or equipment.

The document also uses changing characteristics over time, such as flashing, to attract attention or show a change of state. A higher-priority message is linked to the faster flashing condition, and flashing is used for immediate action, discrepancy between commanded and actual state, or a transition period.

Acoustic signals

prEN IEC 60073:2026 allows acoustic signals when attention is needed, the information is short and transitory, visual coding is restricted, or a supplementary or redundant signal is needed. Acoustic signals must be audible and clearly distinguishable in the intended reception area, and they must not be confused with the emergency evacuation signal.

The standard ties meanings to sound patterns such as sweeping sounds, bursts of sounds, continuous sound and alternating pitch. It also says normal safe conditions should be silent, so sound is reserved for situations where it adds value.

Tactile signals

prEN IEC 60073:2026 permits tactile signals only in restricted cases, for example to draw attention to a hazardous situation. They must be directly and continuously perceived through contact, and they are limited to skilled or instructed persons.

This matters when a user cannot rely on sight or sound alone, but it also prevents overuse of tactile coding. Tactile signals are never meant to be the only means of communication.

Indication modes and HMI actuators

prEN IEC 60073:2026 distinguishes alerting, indication and confirmation modes for both indicators and actuation. It applies different meanings in Tables 7 to 10 for safety, process condition, equipment state and HMI actuators.

For HMI actuators, the most important rules are practical and safety-related. EMERGENCY STOPPING and EMERGENCY SWITCHING-OFF actuators are identified by RED, with YELLOW as the background colour. STOP or OFF actuators use WHITE, GREY or BLACK, with BLACK preferred, while START or ON actuators use WHITE, GREY or BLACK, with WHITE preferred. Illuminated HMI actuators are divided into types a, b and c, and the document also requires emergency operations shown on video display screens to remain visible and accessible from the operator’s working position.

What terms does prEN IEC 60073:2026 define?

• Coding - systematic representation of specific signals or values by another set of signals, under definite rules.
• Indicator - a mechanical, optical or electrical device, or part of one, that provides visual, acoustic or tactile information.
• HMI actuator - a part of the human-machine interface subject to direct human intervention, such as a knob, push-button, mouse, keyboard, touch sensitive screen or voice actuator.
• Human-machine interface (HMI) - a system that enables direct communication between a human and a process or equipment for monitoring and control.
• Visual signal - a phenomenon that uses visual perception to convey information.
• Acoustic signal - an audible signal that uses auditory perception to convey information.
• Tactile signal - a phenomenon that uses tactile perception to convey information.
• Mechanical indicator - an indicator built into a mechanical or electromechanical switching device that shows OPEN, CLOSED or an intermediate position and is not intended as an HMI actuator.

Who uses prEN IEC 60073:2026?

prEN IEC 60073:2026 is used by IEC technical committees preparing safety publications, because it is a Basic safety publication. It is also relevant to machine builders, control-panel designers, automation engineers, process engineers, maintenance teams and safety specialists who define indicator colours, alarms and actuator markings.

The standard is especially useful in industrial environments where operators monitor and control equipment or processes. That includes simple installations with one indicator light as well as larger control stations with many devices, displays and operating modes.

What changed in prEN IEC 60073:2026 from the previous edition?

prEN IEC 60073:2026 cancels and replaces the sixth edition published in 2002. The document says this seventh edition is a technical revision.

The stated changes are:

• the title was modified to be gender neutral
• the definition of terms was updated
• the definition of information was added
• requirements based on outdated technology were removed
• wording was improved to make requirements clearer
• the word actuator was replaced by HMI actuator throughout the document

Which standards are used with prEN IEC 60073:2026?

• IEC Guide 104 - guidance for preparing safety publications and using basic safety publications.
• IEC 60027 (all parts) - letter symbols used in electrical technology.
• IEC 60050(845) - lighting vocabulary used for terms such as light signal, hue and brightness.
• IEC 60417 (all parts) - graphical symbols for use on equipment.
• IEC 60447 - actuating principles for man-machine interface controls.
• IEC 60617 (all parts) - graphical symbols for diagrams.
• ISO/IEC Guide 51 - general safety-aspect guidance for standards.
• ISO 3864 - safety colours and safety signs.
• ISO 7000 - graphical symbols for use on equipment.
• ISO 8201 - audible emergency evacuation signal.
• ISO 11429 - auditory and visual danger and information signals.
• CIE Publication No. 2-2 (TC 1.6) - colours of light signals.
• IEC 60204-1 - cited as an example for emergency-stop devices.

What does the prEN IEC 60073:2026 document contain?

The document contains coding tables that link colour, shape, acoustic pattern, vibration and position to meanings for safety, process condition and equipment state. It also includes application tables for indication and actuation modes, plus separate tables for HMI actuators.

Annex B gives a worked colour-coding example for a test station, showing how one indicator can combine colour, time and position coding to avoid ambiguity. Annex C provides example visual, acoustic and tactile signals that can be used when designing interfaces, alarms, operating stations and related documentation.

Annex A deals with mechanical indicators, including marking rules and how colours are used when symbols or words are present.

SLOVENSKI STANDARD
01-oktober-2026
Osnovna in varnostna načela za vmesnik človek-stroj, označevanje in
identifikacijo - Načela kodiranja za indikatorje in aktuatorje
Basic and safety principles for man-machine interface, marking and identification -
Coding principles for indicators and actuators
Grund- und Sicherheitsregeln für die Mensch-Maschine-Schnittstelle, Kennzeichnung -
Codierungsgrundsätze für Anzeigengeräte und Bedienteile
Principes fondamentaux et de sécurité pour l'interface homme-machine, le marquage et
l'identification - Principes de codage pour les indicateurs et les organes de commande
Ta slovenski standard je istoveten z: prEN IEC 60073:2026
ICS:
01.070 Barvno kodiranje Colour coding
13.110 Varnost strojev Safety of machinery
29.020 Elektrotehnika na splošno Electrical engineering in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

3/1785/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60073 ED7
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-08-14 2026-11-06
SUPERSEDES DOCUMENTS:
3/1695/CD, 3/1778/CC
IEC TC 3 : DOCUMENTATION, GRAPHICAL SYMBOLS AND REPRESENTATIONS OF TECHNICAL INFORMATION
SECRETARIAT: SECRETARY:
Sweden Mr Mikael Törnkvist
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 3 Horizontal Basic Safety
TC 2,SC 3C,TC 9,SC 17A,TC 18,TC 22,SC 22G,SC
22H,TC 23,SC 23B,SC 23E,SC 23H,SC 23J,TC 27,TC
31,SC 31M,SC 34D,SC 37A,TC 44,SC 45A,TC 61,TC
62,TC 64,SC 65B,TC 66,TC 69,TC 72,TC 79,TC 80,TC
85,TC 88,TC 96,TC 100,TC 108,TC 116,SC 121A,SC
121B
ASPECTS CONCERNED:
Safety
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submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Basic and safety principles for man-machine interface, marking and identification - Coding principles
for indicators and actuators
PROPOSED STABILITY DATE: 2032
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IEC CDV 60073 © IEC 2026
CONTENTS
Contact . 2
CONTENTS . 1
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Coding principles . 9
4.1 General . 9
4.2 Visual signals . 11
4.2.1 General . 11
4.2.2 Coding by colours . 11
4.2.3 Codingby shapes or position or both . 13
4.2.4 Coding by changing of characteristics over time . 14
4.3 Acoustic signals . 14
4.4 Tactile signals . 15
5 Application requirements . 16
5.1 Indication modes . 16
5.2 Actuation modes . 7
5.2.1 General . 7
5.2.2 Non-illuminated HMI actuators . 7
5.2.3 Illuminated HMI actuators . 8
5.3 HMI actuators as a part of pictorial presentation on a video display terminal . 9
5.3.1 Identification of HMI actuators . 9
5.3.2 Emergency operations . 9
Annex A (normative) Special requirements for mechanical indicators . 10
A.1 Marking . 10
A.2 Colours . 10
A.2.1 Mechanical indicators with graphical symbols or words . 10
A.2.2 Mechanical indicators without graphical symbols or words . 10
Annex B (informative) Example for the application of indication coding (using colours) . 11
Annex C (informative) Examples of visual, acoustic and tactile signals . 13
Bibliography . 16

Figure B.1 – Indicators and actuators associated with a test station . 11

Table 1 – . 4
Table 2 – Means of coding and their characteristics to be considered . 10
Table 3 – Meaning of colours – General principles . 12
Table 4 – Meaning of shapes – General principles . 13
Table 5 – Meaning of acoustic codes – General principles . 15
Table 6 – Meaning of tactile signals – General principles . 16
Table 7 – Meaning of indication signals with respect to the safety of persons, property
aor the environment . 1
IEC CDV 60073 © IEC 2026
Table 8 – Meaning of indication signals with respect to the condition of the process . 2
Table 9 – Meaning of indication signals with respect to the state of equipment . 4
Table 10 – General meaning of the signals for HMI actuators . 5
Table B.1 – Information to be coded . 12
Table B.2 – Complete information concept for the example . 12
Table C.1 – Examples of visual signals . 13
Table C.2 – Examples of acoustic signals . 14
Table C.3 – Examples of tactile signals . 15

IEC CDV 60073 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Basic and safety principles for man-machine interface, marking and
identification - Coding principles for indicators and actuators

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) IEC draws attention to the possibility that the implementation of this document may involve
the use of (a) patent(s). IEC takes no position concerning the evidence, validity or applicability
of any claimed patent rights in respect thereof. As of the date of publication of this document,
IEC [had/had not] received notice of (a) patent(s), which may be required to implement this
document. However, implementers are cautioned that this may not represent the latest
IEC CDV 60073 © IEC 2026
information, which may be obtained from the patent database available at https://patents.iec.ch.
IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60073 has been prepared by IEC technical committee 3: Basic and
safety principles for man-machine interface, marking and identification. It is an international
standard.
This seventh edition cancels and replaces the sixth edition published in 2002. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the title of the document has been modified to be gender neutral
b) definition of terms has been updated
c) definition of the term "information" is provided
d) requirements based on out-dated technology has been removed;
e) wording improved to make requirements clearer;
f) the word "actuator" is replaced by "HMI actuator" throughout the document.
It has the status of a Basic safety publication in accordance with IEC Guide 104.
The text of this International Standard is based on the following documents:
Table 1 –
FDIS Report on voting
3/XX/FDIS 3/XX/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English [change
language if necessary].
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
Annex A forms an integral part of this standard.
Annex B and Annex C are for information only.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC CDV 60073 © IEC 2026
INTRODUCTION
Supervision and intervention are the principal tasks of personnel engaged in the monitoring and
control of equipment or processes.
Indicators for the representation of conditions, and actuating devices to enable intervention
under normal and fault conditions, are essential to this purpose.
The information presented should meet the needs of the users for the monitoring and control
tasks which they are required to perform, for example, in extensive industrial processes.
Safety and ergonomic aspects should also be taken into account. The use of only a single
means of coding is often insufficient to ensure unambiguous representation of information.
Apart from an unambiguous marking of the indicating and actuating devices, there is a
requirement for a clear and consistent system of coding.
The choice of a code will depend on the information which it is intended to impart. This may
relate to the state of equipment (or part of it), to the condition of a process, and/or to the effects
which this condition has on persons, property and the environment.
The user is required to decide on which of these criteria the coding for the relevant application
is to be based.
IEC CDV 60073 © IEC 2026
1 Scope
This International Standard establishes general rules for assigning particular meanings to
certain visual, acoustic and tactile indications in order to
a) increase the safety of persons, property or the environment through the safe monitoring and
control of the equipment or process;
b) facilitate the proper monitoring, control and maintenance of the equipment or process;
c) facilitate the rapid recognition of control conditions and HMI actuator positions.
This standard is for general application:
– from simple cases such as single indicator lights, push-buttons, mechanical indicators, light
emitting diodes (LEDs) or video display screens to extensive control stations which may
include a wide variety of devices for controlling an equipment or process;
– where the safety of persons, property or the environment is involved, and also where the
above-mentioned codes are used to facilitate the proper monitoring and controlling of
equipment;
– where a particular kind of coding is to be assigned by a technical committee to a special
function.
This BASIC SAFETY PUBLICATION focusing on SAFETY essential requirement is primarily
intended for use by technical committees in the preparation of SAFETY publications in
accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
basic safety publications in the preparation of its publications.
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 Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
IEC 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050(845), International Electrotechnical Vocabulary (IEV) Lighting
IEC 60417 (all parts), Graphical symbols for use on equipment
IEC 60447, Man-machine interface (MMI) – Actuating principles
IEC 60617 (all parts), Graphical symbols for diagrams
ISO/IEC Guide 51, Safety aspects – Guidelines for their inclusion in standards
ISO 3864, Safety colours and safety signs
ISO 7000, Graphical symbols for use on equipment – Index and synopsis
ISO 8201, Acoustics – Audible emergency evacuation signal
IEC CDV 60073 © IEC 2026
ISO 11429, Ergonomics – System of auditory and visual danger and information signals
CIE (International Commission on Illumination): Publication No. 2-2 (TC 1.6), Colours of light
signals
3 Terms and definitions
For the purposes of this standard, the following definitions apply.
3.1
coding
systematic representation of specific signals or values by another set of signals, which
has to conform to a definite set of rules
[SOURCE: IEC 660050-181:—, 181-14-11]
3.2
indicator
mechanical, optical or electrical device or a part of device providing visual, acoustic or tactile
information
[SOURCE: IEC 60050-181:—, 181-14-12]
3.3
acoustic signal
audible signal
phenomenon utilizing auditory perception in humans to convey information
[SOURCE: IEV 60050-181:—, 181-14-09, modified — The synonym added.]
3.4
tactile signal
phenomenon utilizing tactile perception in humans to convey information
[SOURCE: IEV 60050-181:—, 181-14-10]
3.5
visual signal
phenomenon utilizing visual perception in humans to convey information
[SOURCE: IEV 60050-181:—, 181-14-08]
3.6
HMI actuator
part of the human-machine interface which is subject to a direct human intervention
EXAMPLE Knob, push-button, push-push button, push-pull button, roller, plunger, mouse, light pen, keyboard,
touch sensitive screen, voice actuator.
Note 1 to entry: For the purposes of this standard, the HMI actuator in the case of an interactive screen display is
considered to be that part of the screen display which represents the HMI actuator function.
[SOURCE: IEC 60050-181:—, 181-14-02]
IEC CDV 60073 © IEC 2026
3.7
mechanical indicator
indicator, forming an integral part of a mechanical or electromechanical switching device, that
indicates whether the switching device is in the OPEN, CLOSED or an intermediate position,
and is not intended as an HMI actuator
[SOURCE: IEC 60050-181:—, 181-14-13]
3.8
human-machine interface
HMI
system enabling a direct means of communication between a human and a process or
equipment, enabling the human to monitor and control the equipment or process
Note 1 to entry: Such systems can include manually operated HMI actuators, indicators and screens
[SOURCE: IEC 60050-181:—, 181-14-01]
3.9
signal light
device designed to emit a light signal
[SOURCE: IEC 60050-845:2020, 845-31-004]
3.10
light emitting diode
LED
solid-state device embodying a p-n junction, emitting optical radiation when excited by an
electric current
[SOURCE: IEC 60050-845:2020, 845-27-050, modified - Notes to entry removed.]
3.11
illuminated actuator
HMI actuator with an integrated light source providing a visual signal by illumination
Note 1 to entry: The operation of the light source can be related to or independent of the HMI actuator action.
[SOURCE: IEC 60050-181:—, 181-14-06]
3.12
hue
attribute of a visual perception according to which an area appears to be similar to one of the
colours red, yellow, green, and blue, or to a combination of adjacent pairs of these colours
considered in a closed ring
[SOURCE: IEC 60050-845:2020, 845-22-067, modified - Note 1 to entry removed.]
3.13
brightness
attribute of a visual perception according to which an area appears to emit, transmit or reflect,
more or less light
[SOURCE: IEC 60050-845:2020, 845-22-059, modified - Notes to entry removed.]
3.14
saturation
colourfulness of an area judged in proportion to its brightness
IEC CDV 60073 © IEC 2026
Note 1 to entry: For given viewing conditions and at luminance levels within the range of photopic vision, a colour
stimulus of a given chromaticity exhibits approximately constant saturation for all luminance levels, except when the
brightness is very high.
[SOURCE: IEC 60050-845:2020, 845-22-073, modified - Note 2 to entry removed.]
3.15
contrast
perceived contrast
assessment of the difference in appearance of two or more parts of
a field seen simultaneously or successively
EXAMPLE Brightness contrast, lightness contrast, colour contrast, simultaneous contrast, successive contrast
[SOURCE: IEC 60050-845:2020, 845-22-089, modified - Note 1 to entry removed.]
3.16
information
knowledge represented for communication, storage or processing
Note 1 to entry: Information can be represented, for example, by signs, symbols, pictures or sounds.
[SOURCE: IEC 60050-181:—, 181-01-03]
3.17
computer screen
video display terminal
screen
display
monitor
VDT
device that gives a visual representation of data
[SOURCE: IEC 60050-171: 2019, 171-04-39, modified – visual display terminal and VDT added
as synonyms and "output device" replaced by "device".]
3.18
emergency switching-off
operation intended to initiate the remove electric power from an equipment, machine, system
or installation to avert or alleviate a hazardous situation
[SOURCE: IEC 60447:—, 3.20]
3.19
emergency stopping
operation intended to stop as quickly as possible a movement which has become dangerous
[SOURCE: IEC 60050-826:2022, 826-17-03]
4 Coding principles
4.1 General
Coding principles shall be established at an early stage of system design and shall be consistent
with those used for other equipment within the same plant or process.
For the selection of a specific code, consideretions shall be taken to the task to be performed
of the personell and the operating conditions.
IEC CDV 60073 © IEC 2026
One or more of the following means of indication coding should be applied:
Visual signals:
– by colour;
– by shape;
– by position;
– by changing characteristics over time (flashing).
Acoustic signals:
– by type of sound;
– by pure tone;
– by changing characteristic over time.
Haptic signals:
– by shape;
– by force;
– by vibration;
– by position;
– by changing characteristic over time.
Table 2 provides examples of characteristics to be considered for different codings
The meaning of the selected codes shall be unambiguous and shall be explained in the
associated documentation of the equipment , process or plant.
Table 2 – Means of coding and their characteristics to be considered
Means Characteristic
Visual signals
– Hue
Colour
– Saturation
– Brightness
– Contrast
– Figure (alphanumeric, pictographs, graphical symbols, lines)
Shape
– Form (character font, size, line width)
– Texture (line type, shading, dotting)
– Location (absolute, relative)
Position
– Orientation (with or without reference system)
Time Changing over time (flashing):
– Brightness
– Colour
– Shape
– Position
Acoustic signals
– Tone
Type of sound
– Noise
– Spoken message
– Selected frequency
Pure tone
IEC CDV 60073 © IEC 2026
Means Characteristic
Time Change of
– Frequency composition over time
– Sound volume over time
– Total duration
Tactile signals
– Form
Shape
– Surface roughness
– Amplitude
Force
– Amplitude
Vibration
– Frequency
– Location (absolute, relative)
Position
– Orientation (with or without reference system)
Time Change of:
– Force over time
– Vibration over time
4.2 Visual signals
4.2.1 General
For visual signals, colour and changing of elements over time (flashing) are the most effective
visual means of attracting attention. Therefore these means shall be used with consistent
meanings; colours for giving priority and flashing for attracting attention.
Colour shall not be the sole means of coding. The colour shall be within the chromaticity
boundary specified in ISO 3864-4 during the expected life of the indicators and HMI actuators
under the specified operating conditions.
Where the meaning of colour relates to the safety of persons or the environment (see 4.2.2.2)
supplementary means of coding shall be provided.
Where operating conditions prohibit the application a colour with a specific information, either:
– other means for visual signals (see 4.2.3), or
– other indication methods (see the following subclauses of Clause 4),
shall be provided
4.2.2 Coding by colours
4.2.2.1 General
Specific meanings are assigned to specific colours (see Table 3) and these colours shall be
easily identifiable and distinguishable from the background colour and any other assigned
colours. Certain colours are reserved for safety applications.
The number of colours used in a given application should be kept to a minimum.
The following colours for indicators and HMI actuators are specified in this document:
RED, YELLOW, GREEN, BLUE, BLACK, GREY, WHITE.
Other colours may be used but their meanings are not defined in this document.
IEC CDV 60073 © IEC 2026
A colour shall be specified by an appropriate combination of íts hue, saturation, brightness or
contrast charactistics in accordance with the requirements of ISO 3864 series.
Where colour is the sole means of coding, the colour shall be within the chromaticity boundary
specified in ISO 3864-4 during the expected life of the indicators and HMI actuators under the
specified operating conditions.
For the exact definitions see:
– for surface colours:, see ISO 3864;
– for emitted lights, see CIE S 004/E:2001
NOTE 1 Perceived colour is due to the combined effects of emitted light, if any (e.g. of a signal light) and incident
light (e.g. of the working place).
NOTE 2 The colour GREY is not defined in ISO 3864.
4.2.2.2 Choice of colours
The general principles for the meaning of colours for the indication of information are specified
in Table 3.
Table 3 – Meaning of colours – General principles
Colour Meaning
Safety of persons or Condition of process State of equipment
environment
RED Danger Emergency Faulty
YELLOW Warning/caution Abnormal Abnormal
GREEN Safe Normal Normal
BLUE Mandatory significance
WHITE No specific meaning assigned
GREY
BLACK
Where indicators connected in parallel, mounted at different locations, have different meanings
in their location context, different colours may be used for the indicators (see Annex B).
The colour to be displayed by indicators shall be chosen with regard to the information to be
imparted.
The colour coding shall be selected according :
– Table 7 when the coding is related to safety of persons or the environment;
– Table 8 when the coding is related to the condition of the process;
– Table 9 when the coding is related to state of the equipment.
The colour coding applied shall not shall cause risk of confusion
4.2.2.3 Colours on video display screens
The application of colours listed in 4.2.2.1 shall be restricted to that purpose as given in 4.2.2.2.
Other kind of information may be transmitted using other colours provided no misunderstanding
may arise.
Colours shall contrast adequately with adjacent colours and with the background of the display.
oSIST prEN
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