Unit Symbol Rules
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Definition
The BIPM conventions governing how SI unit symbols are written: upright (roman) type, case-sensitive, no plural forms, no trailing periods, and separated from the numeral by a space.
Explanation
Correct: 5 kg, 273.15 K, 100 MHz, 9.81 m/s². Incorrect: 5 Kg (K is kelvin, not kilo), 100 mhz (MHz must be capitalized), 5kgs (no plural, no space), 5 m. (no period). The prefix and unit form a single symbol without a space: km, not k m. These rules prevent ambiguity: ‘ms’ means milliseconds, while ‘mS’ means millisiemens.
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