International Standards and Conformity Assessment for all electrical, electronic and related technologies
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28 Figures

28.1 Purpose or rationale

Figures are a graphical means of representation used when they are the most efficient means of presenting information in an easily comprehensible form.


Photographs and other media may be used if it is not possible to represent the concept as a line drawing.


28.2 Title

It is recommended to provide a concise figure title.


28.3 Numbering and subdivision

28.3.1 Figure designation

Figures shall be designated "Figure" and numbered with Arabic numerals, beginning with 1. A single figure shall be designated "Figure 1". This numbering shall be independent of the numbering of the clauses and of any tables.

In annexes, the figure numbering restarts and the number is preceded by the annex letter (e.g. Figure A.1, etc.).


When a figure is continued over several pages, it can be useful to repeat the figure designation, followed by the title (optional) and by "(1 of #)", where # is the total number of pages on which the figure appears.



Figure x (1 of #)

28.3.2 Subfigures

In general, the use of subfigures should be avoided whenever possible since it complicates document layout and management.

Only one level of subdivision of a figure is permitted. Subfigures shall be identified by a lower case letter [e.g. Figure 1 may comprise subfigures a), b), c), ...]. Other forms of identification of the subfigures such as 1.1, 1.2, ..., 1-1, 1-2, ..., etc. shall not be used.


Separate keys, notes and footnotes for subfigures are not permitted.




Statement concerning units




Drawing or illustration





Drawing or illustration




a) Subtitle


b) Subtitle




Paragraphs (containing requirements) and notes to the figure

Footnotes to the figure

Figure x – Title



28.4 Referencing

Each figure shall be explicitly referred to within the text.


Use, for example, the following forms for references to figures and subfigures:

  • "Figure 3 illustrates…";
  • "See Figure 6 b)".

28.5 Specific principles and rules

28.5.1 Standards used in the creation of graphical content

The standards listed in Table 9 provide information regarding the creation of graphical content.






IEC 61082-1

Preparation of documents used in electrotechnology – Part 1: Rules

Graphical symbols

IEC 62648

Graphical symbols for use on equipment – Guidelines for the inclusion of graphical symbols in IEC publications


IEC 80416-1

Basic principles for graphical symbols for use on equipment – Part 1: Creation of graphical symbols for registration


ISO/IEC 81714-1

Design of graphical symbols for use in the technical documentation of products – Part 1: Basic rules

Line types

ISO 128-20

Technical drawings – General principles of presentation – Part 20: Basic conventions for lines


ISO 129

(all parts)

Technical drawings – Indication of dimensions and tolerances

Dimensional and geometrical product specifications

ISO 1101

Geometrical product specifications (GPS) – Geometrical tolerancing – Tolerances of form, orientation, location and run-out


ISO 128-30

Technical drawings – General principles of presentation – Part 30: Basic conventions for views

Flowcharts and organigrams

ISO 5807

Information processing – Documentation symbols and conventions for data, program and system flowcharts, program network charts and system resources charts

28.5.2 Choice of letter symbols, style of lettering

Letter symbols used in figures to represent general cases of angular or linear quantities shall be in accordance with ISO 80000-3. Subscripts can be used where necessary to distinguish between different applications of a given symbol.


Various lengths, l, on a drawing should be written with descriptor indices, e.g. l1, l2, l3, and not, for instance, A, B, C, etc. or a, b, c, etc. The main symbols used in drawings from ISO 80000-3 are given in Table 10.


Table 8 – Main symbols used in drawings from ISO 80000-3





l, L


b, B


h, H


d, δ


r, R

Radial distance

rQ, ρ


d, D

Length of path



d, r

Cartesian coordinates

x, y, z,

Position vector




Radius of curvature



Lettering on technical product documentation shall be in accordance with the ISO 3098 series. Italic letters shall be used for variable quantities.

The vertical (upright) style shall be used for all other lettering.

When all units for a quantity are the same, a suitable statement (e.g. "Dimensions in millimetres") shall be placed above the right-hand corner of the figure.


See Figure 5.


1   mandrel shank
2   blind rivet head


The mandrel shall be designed such that the blind rivet end deforms during installation, and the shank can expand.


NOTE Figure # illustrates a type A rivet head.


a   The break area shall be milled.

b   The mandrel head is commonly chromium plated.


Figure 5 – Example illustrating the elements of a figure

28.5.3 Key and labels to figures

Figures shall be language neutral in order to facilitate translation, using key references or figure footnotes (see Figure 5) instead of textual descriptions (in accordance with ISO 6433).


In graphs (see Figure 6 ), labelling of curves, lines, etc. shall be replaced by key references. Labelling on the axes shall not be replaced by numerical key references, which could be confused with numeric values.


w  mass fraction of gelatinized kernels, expressed in per cent
t  cooking time, expressed in minutes

t90 cooking time, expressed in minutes

P cooking time, expressed in minutes


NOTE These results are based on a study carried out on three different types of kernel.


a   The time t90 was estimated to be 18,2 min for this example.


Figure 6 – Example of a graph


In flowcharts and organigrams, the use of textual descriptions is permitted (see 28.6.4).

28.5.4 Notes to figures

A single note in a figure shall be preceded by "NOTE", placed at the beginning of the first line of the text of the note. See Figure 5 . When several notes occur in the same figure, they shall be designated "NOTE 1", "NOTE 2", "NOTE 3", etc. The numbering restarts for each new figure.

Notes to figures shall not contain requirements or any information considered indispensable for the use of the document. Any requirements relating to the content of a figure shall be given in the text, in a footnote to the figure or as a paragraph between the figure and its title. Notes to figures do not need to be referred to.


Table 8 summarizes how to use notes and footnotes within documents.

28.5.5 Footnotes to figures

Footnotes to figures are numbered independently from footnotes to the text.
Footnotes to figures shall be distinguished by superscript lower case letters, starting with "a". The footnotes shall be referred to in the figure by inserting the same superscript lower case letter. See Figure 5.

Footnotes to figures may contain requirements.


Table 8 summarizes how to use notes and footnotes within documents.


28.6 Types of figure

28.6.1 Mechanical engineering drawings

Mechanical engineering drawings shall be prepared in accordance with relevant ISO standards (listed in 28.5.1). Different views, details and sections of a component or multicomponent object shall be presented in conformity with ISO 128-30, ISO 128-34, ISO 128-40 and ISO 128-44. Different views, details and sections of a component or multicomponent object shall not be presented as subfigures.


See Figure 7.



Figure 7 – Example of a mechanical engineering drawing


28.6.2 Graphical symbols

Graphical symbols for use on equipment shall be in accordance with IEC 60417 and ISO 7000. Public information symbols shall be in accordance with ISO 7001. Safety signs shall be in accordance with ISO 7010.

For purposes of consistency and coherence, IEC TC 3, IEC SC 3C and ISO/TC 145 are responsible for the standardization of graphical symbols and safety signs. If an adequate symbol or safety sign does not exist in the IEC and ISO databases, contact IEC TC 3, IEC SC 3C and ISO/TC 145 in order to register a standardized symbol.


Table 11 gives an overview of the categories of graphical symbol.


Table 11 – Categories of graphical symbol


Category of graphical symbol Basic message Location Design principles Overview Responsible committee
Public information symbols Location of service or facility In public areas ISO 22727 ISO 7001 ISO/TC 145/SC 1
Safety signs (symbols) Related to safety and health of persons In workplaces and public areas ISO 3864-1
ISO 3864-3
ISO 7010 ISO/TC 145/SC 2
Product safety labels Related to safety and health of persons On products ISO 3864-2
ISO 3864-3
ISO/TC 145/SC 2
Graphical symbols for use on equipment Related to equipment On equipment IEC 80416-1
ISO 80416-2
IEC 80416-3
ISO 7000
IEC 60417
ISO/TC 145/SC 3
Technical product documentation symbols (Product representation) Technical product documentation (drawings, diagrams, etc.) ISO 81714-1 ISO 14617
IEC 60617
ISO/TC 10/SC 10


See Figure 8.


IEC 60417-5012

Figure 7 – Example of a graphical symbol


28.6.3 Circuit diagrams and connection diagrams

Diagrams, such as circuit diagrams and connection diagrams, for example for test circuits, shall be prepared in accordance with IEC 61082-1. Graphical symbols used in schematic diagrams shall be in accordance with IEC 60617 and ISO 14617. Reference designations shall be in accordance with IEC 81346. Signal designations shall be in accordance with IEC 61175-1. See Figure 9 .



Figure 9 – Example of a circuit diagram


28.6.4 Flowcharts

Flowcharts shall be prepared in accordance with ISO 5807. See Figure 10 .


Figure 10 – Example of a flowchart