Conventions for diagrams

Structural design principles and conventions for diagrams

Good diagrams use the following structural design principles and conventions:

• The reading direction runs from top left to bottom right. Alternatively, another convention, such as clockwise rotation, is used to direct readers through the information.
• Alignment and spacing are used effectively to indicate sequence and hierarchy.
• Consistent styling is used for similar elements, and different styling is used for dissimilar elements.
• Colour is used meaningfully.
• Only content or detail that is directly relevant is included.
• Design elements are minimised so that the content, not the design, is visually prominent (e.g. borders around text frames are removed).
• Perspective, exploded or zoomed inset views are included, if required.
• Text snippets and labels are clear and easy to read.
• The legend is clear.
• Alternative text is used for accessibility, if published online.

Figure name or title

The following principles are recommended:

• Place the figure title as its own paragraph below the diagram, not within the diagram. This convention should also be used for web-based publications.
• Number figures consecutively within the document (e.g. Figure 1, Figure 2, Figure 3), or by section or chapter (e.g. Figure 2.1, Figure 2.2, Figure 4.1, Figure B5). Numbering by section is useful because changes in one section will not affect figure numbering in another section. This is especially important in long documents or those that have many figures.
• Use a title that describes the diagram content, including the period that the data cover, if appropriate:

• Use minimal capitalisation (only capitalise the first letter of the first word of the title and proper nouns).
• Use minimal punctuation to keep figure titles clean and uncluttered: follow figure numbers with a tab, not a colon, and do not place a full stop at the end. Using a tab also helps align the names properly in an automatically generated contents list of figures.
• Spell out abbreviations in full in the title, wherever possible. Put any necessary detail in explanatory figure notes. The title should not cover more than 2 lines (preferably 1 line).
• For a series of diagrams, give the same information in the same order.