ref: dimensional analysis

Tracking quantities by their units.

For example, we can ask whether an inch is more or less than a centimeter, as there is a conversion:

cm = in *2.54 (cm/in)

but not whether a centimeter is more or less than an hour, as the units don't convert.

Type-checking in languages like C++ is an implementation of this idea, in which quantities perforce declare units.

See: [ (link)] 2017 [171108]