4. Acronyms, notations, and symbols

The unit of each quantity shall be expressed using the International System. Base units: length in meters (m), mass in kilograms (kg), time in seconds (s), temperature in kelvins (K), amount of substance in moles (mol). Derived units, expressed in terms of base units: pressure in pascals (Pa: kg · m ^–1 · s ^–2 ), energy in joules (J: kg · m ² · s ^–2 or Pa · m ³ ), power in watts (W: kg · m ² · s ^–3 or J · s ^–1 ), solid angle in steradians (sr: m ² · m ^–2 ...