Drafting IEC publications
Formulae, equations and variable symbols
(The full requirements are described in the ISO/IEC Directives Part 2:2011, 6.6.10.)
- The symbols used in each formula should be defined, either in the text above or immediately below the formula.
- Symbols for variable quantities are to be written in italics.
Note: We recommend the use of Times New Roman type so as to avoid confusion between the letters (uppercase i) and (lowercase L), for example.
- Subscripts are written in Arial upright type, unless they represent symbols for variable quantities (in which case, they are written in italics).
- If it is necessary to number some or all of the formulae in a document in order to facilitate cross-reference, Arabic numbers in parentheses are used, beginning with (1).
- Symbols, rather than descriptive names, shall be used in formulae.