(ISO: Geneva) -- ISO recently published a new version of the SI Guide, a small manual for the use of the International System of Units (SI [Système International d’Unités]).

The SI is a comprehensive metric and decimal system based on units and derived units. The seven base units are length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.

For the first time, this new edition of the SI Guide includes:

• One new derived unit: the katal, symbol kat (1 kat = 1 mol/s) for the quantity of catalytic activity—essentially used in clinical chemistry, it can also be used in other fields of chemistry

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