Figures, graphs and charts
General principles
All illustrations (photographs, diagrams, graphs, maps) should be treated as figures,
numbered consecutively in Arabic numerals in the order in which they are referred to in the text and supplied with captions. The numbering sequence should normally be continued throughout the document, including appendices, but started again for each annex. Essentially the same information should not be presented in both a figure and a table (and/or the main text).
Every figure must be specifically referred to in the text, e.g. “Figure 3 shows”, “This is
shown in Figs 4(a) and (b)”, “difference is clear (Figs 6(c)–(e))”.
Legends and labels
Lettering in figures should be kept to a minimum. Each item of information should preferably begin with an initial capital. Otherwise, capitals are required only for proper nouns.
A legend (e.g. an explanation of shading or symbols) should be placed on the diagram if there is room. It can otherwise be placed below the figure. If a legend is short and simple it can form part of the caption.
Axes of graphs should be labelled with the name of the measured quantity, beginning with an initial capital, followed by the unit of measurement in parentheses, e.g. Diffusion rate (mg/s). If a symbol is also given, it should be preceded by a comma, e.g. Time, t (ms). The label of a vertical axis should be placed parallel to the axis, unless it is very short. Repetitive numbering at the axes can be avoided by adding any multiplier to the label. For example, instead of numbering the divisions of an axis from 1 × 105 to 6 × 105 measuring a current I in amperes, the axis can be labelled I (105 A) and the divisions simply numbered from 1 to 6.
If the axis of a graph has a numbered scale, it does not require an arrow as well.
Figure captions
Every figure must have a caption. Captions should be concise, should not repeat
information already contained in the text or a table, and should not contain information whose proper place is in the text.
Figure numbers
In principle, figures are numbered consecutively throughout the document. However, in a long, complex document divided into chapters, the figures (as well as the tables, equations and references) are numbered from 1 in each chapter. Thus Fig. 3.5, Fig. 8.14 refer to figures in Chapters 3 and 8, respectively, and the fifth figure in the first appendix would be Fig. I.5.
Reproduction of figures from other publications
If a figure is to be reproduced from another publication, the originator is responsible for obtaining the necessary written permission from the original author and/or publisher and for supplying a suitable acknowledgement.