The following recommendations apply to diagrams and tables:
1. Diagrams are always better than tables if the shape, variation, or connection between materials is of interest or if interpolation is necessary. If not, tables are preferable.
2. Simplify the table as much as possible without reducing its accuracy and without the need for interpolations (an example of this would be where, if the depth markings on a water tank level are not sufficient, several calculations are required to interpret water level).
3. Leave at least 4 to 5 mm between columns, which are not separated by vertical lines.
4. Where the table columns are long (more than six lines), they should be divided into groups of three or four lines. Leave some space between each group.
5. Diagrams should be drawn so that the numbered axis lines are darker than the unnumbered ones. Where only every tenth line is numbered, the fifth line should also be denser than the others, but less dense than the numbered ones.
6. Avoid combining too many parameters in the same diagram; there should be no more than three. If more parameters are shown, more diagrams must be used.
