ISO DIS 17724 Ed 2:2025(X)
ISO TC 145
Secretariat: BSI
Date: 2025-02-06
Graphical symbols — Vocabulary
© ISO 2025
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Contents
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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This document was prepared by Technical Committee 145 (Graphical Symbols).
This second edition cancels and replaces the first edition (ISO 17724:2003), which has been technically revised.
The main changes compared to the previous edition are as follows:
— Addition of an introduction
— Deletion of definitions which ae not core or which are covered in other ISO TC 145 standards – reduce definitions to 37 from 82
— Renumbering of definitions to match the ISO template numbering
— Update of Bibliography
Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.
Introduction
This document was first published in 2003. It provided a consolidated vocabulary for the graphical symbol sector. Subsequently at ISO/TC 145’s request to make graphical symbols visible online, ISO created the ISO Online Browsing Platform. The ISO Online Browsing Platform (OBP) can be found at https://www.iso.org/obp/ui. This platform contains all the terms and definitions in all ISO deliverables, including those contained in this document. Users of this standard should refer to the ISO OBP as the first source of current terms and definitions. It is anticipated that over time this will remove the need to maintain ISO 17724.
Further terms and definitions for graphical symbols are given in the following documents:
— ISO 3864 series and ISO 17398 (safety colours and safety signs);
— ISO 9186 series (test methods);
— ISO 16069 and ISO 22578 series (safety way guidance systems);
— ISO 20560 series (safety information for the content of piping systems and tanks);
— ISO 20712 series (water safety signs and beach safety flags);
— ISO 22727 (public information symbols);
— ISO 23601 (escape and evacuation plan signs)
— ISO 28564 series (public information guidance systems).
Graphical symbols — Vocabulary
1.0 Scope
This International Standard defines terms relating to graphical symbols, principally symbols for public information safety signs and use on equipement. It does not include terms related to graphical symbols for diagrams [technical product documentation (tpd) symbols].
The definitions are intended to serve as a basis for consideration by those concerned with producing new standards or revising existing ones.
The terms are presented in English alphabetical order.
2.0 Normative references
There are no normative references in this document.
3.0 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
assembly area
designated safe area outside the occupied area where evacuees are expected to assemble
3.2
basic graphical symbol
graphical symbol (3.14) from which a family of graphical symbols can be derived )
3.3
border
band that defines the edge of a sign (3.33) or graphical symbol (3.14)
3.4
caution
signal word used to indicate a potentially hazardous situation which, if not avoided, may result in minor or moderate injury
3.5
character
single letter, numeral, punctuation mark or graphical symbol (3.14)
3.6
chevron
graphical symbol (3.14) that serves a similar purpose to an arrow and is similar to an arrowhead in appearance
3.7
coefficient of retroreflection
〈of a plane retroreflecting surface〉 luminous intensity (I) of a plane retroreflecting material in the direction of observation divided by the product of the illuminance (E⊥) of the retroreflecting surface on a plane perpendicular to the direction of the incident light and its area (A) 
3.8
conspicuity
property of an entity within the visual field which permits it to be more easily detected than the surrounding information
3.9
contrast
difference between the highest and the lowest densities of an image
Note 1 to entry; See also positive contrast (3.25) and negative contrast (3.21)
3.10
corner marking
part of a graphical symbol (3.14) original, four of which define its corners
3.11
danger
signal word used to indicate an imminently hazardous situation which, if not avoided, may result in death or serious injury
3.12
displacement
distance between the centre of a graphical symbol (3.14) and the central line of the normal direction of vision of the user, measured at a right angle to that central line of vision
3.13
factor of distance
z
relationship between the height (h) of a sign (3.33)and the observation distance (l), used to determine observation distances of signs
3.14
graphical symbol
visually perceptible figure with a particular meaning used to transmit information independently of language
3.15
graphical symbol original
graphical symbol (3.14) with which a referent (3.27), a graphical representation and a description of the application are associated
Note 1 to entry: “application” may be understood to be “intended function”
3.16
guidance line
highly visible linear markers forming part of a way guidance system provided to clearly delineate an escape route or define an escape path through an open area
3.17
legibility
property of characters or graphical symbol elements which enables one to be discriminated from another
Note 1 to Entry: Legibility can also be expressed as “visual clarity”, i.e.the, measure of how effectively visual design prioritizes and conveys information” (Dimitrou, 2020). The visual clarity of a screen or page is a result of the graphics, text, white space and layout that are used.
3.18
luminance contrast
k
luminance of the contrast colour, L1, divided by the luminance of the safety colour, L2, where L1 is greater than L2
3.19
luminescence
emission, by atoms, molecules or ions in a material, of optical radiation which for certain wavelengths or regions of the spectrum is in excess of the radiation due to thermal emission from that material at the same temperature, as a result of these particles being excited by energy other than thermal agitation
[SOURCE: IEC 60050-845:1987, 04-18]
3.20
negation element
DEPRECATED negation stroke
graphical symbol (3.14) element intended to negate a graphical symbol’s (3.14) original intended meaning
3.21
negative contrast
contrast made by using white or bright characters on black or dark-coloured background
Note 1 to entry: See also contrast (3.9) and positive contrast (3.25)
3.22
observation distance
l
greatest distance from which a sign (3.33) is legible and conspicuous
3.23
panel
area of a safety sign (3.30) having a distinctive background colour different from adjacent areas of the sign (3.33), or which is clearly delineated by a line, border or margin
3.24
phosphorescent sign
sign (3.33) that uses phosphors as pigmentation and emits light for a period of time after the energy source has been removed
3.25
positive contrast
contrast made by using black or dark characters on white or light-coloured background
Note 1 to entry: See also contrast (3.9) and negative contrast (3.19)
3.26
product safety symbol
graphical symbol (3.14) used on a product safety label l
Note 1 to entry: See also safety symbol (3.31)
3.27
referent
idea or object that a graphical symbol (3.14) is intended to represent
[SOURCE: ISO 9186-1:2014, 3.38]
3.28
registered graphical symbol original
graphical symbol original (3.15) which has been registered by the relevant standards organization as the definitive version
3.29
safety shape
geometric shape to which a safety meaning is attributed
3.30
safety sign
sign (3.33) which gives a general safety message, obtained by a combination of colour and geometric shape and which, by the addition of a graphical symbol (3.14), gives a particular safety message
3.31
safety symbol
graphical symbol (3.14) used together with a safety colour and safety shape (3.29) to form a safety sign (3.33)
3.32
safety way guidance system
SWGS
system to provide conspicuous and unambiguous information and sufficient visual cues to enable people to evacuate an occupied area in an emergency along a specified escape route by using a comprehensive arrangement of visual components, signs and markings
3.33
sign
configuration of visual elements including symbols, text and shapes intended to communicate a given meaning
3.34
sign carrier
material on which the visual elements of a sign (3.33) are directly reproduced
3.35
supplementary sign
sign (3.33) that is supportive of another sign and the main purpose of which is to provide additional clarification
3.36
supplementary text panel
additional area of a safety sign (3.30) that contains text
3.37
symbol set
set of graphical symbols with related referents or graphical symbol elements
3.38
warning
signal word used to indicate a potentially hazardous situation which, if not avoided, could result in death or serious injury
Bibliography
[1] ISO 22727:2007, Graphical symbols — Creation and design of public information symbols — Requirements
[2] ISO 9186‑1:2014, Graphical symbols — Test methods — Part 1: Method for testing comprehensibility
[3] ISO 3864‑1:2011, Graphical symbols — Safety colours and safety signs — Part 1: Design principles for safety signs and safety markings
[4] ISO 3864‑2:2016, Graphical symbols — Safety colours and safety signs — Part 2: Design principles for product safety labels
[5] ISO 3864‑3:2024, Graphical symbols — Safety colours and safety signs — Part 3: Design principles for graphical symbols for use in safety signs
[6] IEC 80416‑1:2006, Basic principles for graphical symbols for use on equipment Part 1: Creation of graphical symbols for registration
[7] IEC 60050‑845:2020, International Electrotechnical Vocabulary (IEV) - Part 845: Lighting
