Pressure measurement
Many other hybrid units are used such as mmHg/cm or grams-force/cm (sometimes as kg/cm without properly identifying the force units). Using the names kilogram, gram, kilogram-force, or gram-force (or their symbols) as a unit of force is prohibited in SI; the unit of force in SI is the newton (N).
Gc (engineering)
In unit systems where force is a derived unit, like in SI units, "g" is equal to 1 and is not needed. In unit systems where force is a primary unit, like in English units, "g" is not equal to 1, and is required to obtain correct results.