Dictionary · Standards & Units
Quantity equation
A mathematical relation between quantities in a system of quantities, independent of units — v = l/t regardless of whether metres or inches are used.
Related terms
More from Standards & Units
Conventional reference scale
A quantity-value scale defined by formal agreement — pH and the practical temperature scales are canonical examples.
VIM (JCGM 200:2012) 1.29
Primary measurement standard
A standard established using a primary reference measurement procedure, or created as an artifact chosen by convention — not calibrated against another standard for the same quantity.
VIM (JCGM 200:2012) 5.4
Numerical value equation
A relation between numerical values that holds only for stated units — the form most spreadsheet formulas quietly are, and the reason unit discipline matters.
VIM (JCGM 200:2012) 1.25
Transfer measurement device
A device used as an intermediary to compare measurement standards — transferring, not holding, the quantity value.
VIM (JCGM 200:2012) 5.9
Derived quantity
A quantity in a system of quantities defined in terms of the base quantities of that system — speed, force, pressure.
VIM (JCGM 200:2012) 1.5
International System of Units (SI)
The system of units based on the ISQ, with unit names, symbols, prefixes, and rules for their use, adopted by the CGPM. Since the 2019 revision all seven base units are defined by fixing the numerical values of seven defining constants.
VIM (JCGM 200:2012) 1.16