Relating SI to the real world Metric system

although si, published cgpm, should, in theory, meet requirements of commerce, science , technology, units of measure have acquired such position within world community used many years come. in order such units used consistently around world, cgpm catalogued such units in tables 6 9 of si brochure. these categories are:

non-si units accepted use international system of units (table 6). list includes hour , minute, angular measures (degree, minute , second of arc) , historic [non-coherent] metric units, litre, tonne , hectare (originally agreed cgpm in 1879)
non-si units values in si units must obtained experimentally (table 7). list includes various units of measure used in atomic , nuclear physics , in astronomy such dalton, electron mass, electron volt, astronomical unit, solar mass, , number of other units of measure well-established, dependent on experimentally-determined physical quantities.
other non-si units (table 8). list catalogues number of units of measure have been used internationally in well-defined spheres including bar pressure, ångström atomic physics, nautical mile , knot in navigation.
non-si units associated cgs , cgs-gaussian system of units (table 9). table catalogues number of units of measure based on cgs system , dating nineteenth century. appear in literature, continued use discouraged cgpm.




^ international bureau of weights , measures (2006), international system of units (si) (pdf) (8th ed.), pp. 124–129, isbn 92-822-2213-6, archived (pdf) original on 2017-08-14