The gravitational metric system (original french term Système des Méchaniciens) is a non-standard system of units, that does not comply with the International System of Units (SI). It is built on the three base quantities length, time and force with base units metre, second and kilopond respectively. Internationally used abbreviations of the system are MKpS, MKfS or MKS (from french mètre-kilogramme-poids-seconde or mètre-kilogramme-force-seconde). However, the abbreviation MKS is also used for the MKS system of units, which, like the SI, uses mass in kilogram as a base unit.