Table 7.7 — EUs not in the scope of SI
Label Symbol Quantity Concept definition EQ label Code Reference type Reference Supplemental references
ANGSTROM Å length ångström; 1 Å = 10-10 m = 10-1 nm = 10-4 μm (exactly). LENGTH 5 PR [ISO 31-1:1992, 1-3.a (remarks)] [ISO 1000:1992, Annex A, 6.3]
ARE a area The product of length and width.
1 a = 1 dam2 = 102 m2 (exactly).
AREA 6 PR [ISO 31-1:1992, 1-5.a (remarks)] [ISO 1000:1992, Annex A, 1-4]
ASTRONOMICAL_UNIT AU length 1 AU = 1,495 978 7 x 1011 m (approximately). LENGTH 7 PR [ISO 31-1:1992, 1-3.B.b]  
BAR bar pressure The force that is exerted per unit area.
1 bar = 105 Pa (exactly).
PRESSURE 8 PR [ISO 31-3:1992, 3-15a (remarks)] [ISO 1000:1992, Annex A, 3-15.1]
BARN b area The product of length and width.
1 b = 100 fm2 = 10-28 m2 (exactly).
AREA 9 PR [ISO 31-10:1992, 10-3.a (remarks)]  
CURIE Ci activity of a radio nuclide The average number of spontaneous nuclear transitions from a particular energy state occurring in an amount of a radionuclide in a small time interval, divided by that interval.
1 Ci = 3.7 x 1010 Bq (exactly).
RADIONUCLIDE-
_ACTIVITY
30 PR [ISO 31-9:1992, 9-33.a (remarks)] [ISO 1000:1992, Annex A, 9-33]
FOOT ft length 1 ft = 0,304 8 m (exactly). LENGTH 51 PR [ISO 31-1:1992, 1-3.A.b]  
GAL Gal acceleration The change in velocity divided by time.
1 Gal = 0,01 m/s2 (exactly).
ACCELERATION 52 PR [ISO 31-1:1992, 1-11.B.a]  
GEOPOTENTIAL_METRE gpm geopotential energy height (geopotential specific energy) A height proportional to the potential energy of mass (geopotential) at this height relative to the geoid.
The geopotential metre varies with geodetic latitude. On <EARTH> at mid-latitudes it equals 0,98 m (approximately).
GEOPOTENTIAL-
_ENERGY_LENGTH
53 IR [WMO182, "geopotential altitude"]  
GON gon plane angle The angle between two half-lines terminating at the same point is defined as the ratio of the length of the included arc of the circle (with its centre at that point) to the radius of that circle.
1 gon = π / 200 rad = 0,015 707 96 rad (exactly).
PLANE_ANGLE 54 PR [ISO 31-1:1992, 1-1.B.a] [ISO 1000:1992, Annex A, 1-1]
HECTARE ha area The product of length and width.
1 ha = 1 hm2 = 104 m2 (exactly).
AREA 62 PR [ISO 31-1:1992, 1-5.a (remarks)]  
KILOPOUND kp mass 1 kip = 453,592 37 kg (exactly). MASS 126 PR [ISO 31-3:1992, 3-1.B.a] [ISO 31-0:1992, 2.3.2.3]
KNOT kn velocity The distance divided by time.
1 kn = 1 nautical mile per hour = 1,852 km/h = 0,514 444 m/s (exactly).
SPEED 128 PR [ISO 31-1:1992, 1-10.b (remarks)] [ISO 1000:1992, Annex A, 1-10]
LIGHT_YEAR l.y. length The distance travelled in 1 year by electromagnetic waves in free space.
1 l.y. = 9,460 730 x 1015 m (exactly).
LENGTH 129 PR [ISO 31-1:1992, 1-3.B.a]  
LONG_TON ton (long) mass 1 long ton (US) = 1 ton (UK) = 1 016,047 kg (exactly). MASS 133 PR [ISO 31-3:1992, 3-1.B.e]  
MILE mile length 1 mile = 1 609,344 m (exactly). LENGTH 148 PR [ISO 31-1:1992, 1-3.A.d]  
MILE_PER_HOUR mile/h velocity The distance divided by time.
1 mile/h = 0,447 04 m/s (exactly).
SPEED 149 PR [ISO 31-1:1992, 1-10.A.b]  
NAUTICAL_MILE none length 1 nautical mile = 1 852 m (exactly). LENGTH 158 PR [ISO 31-1:1992, 1-3.a (remarks)]  
PARSEC pc length The distance at which 1 astronomical unit subtends an angle of 1 second of arc.
1 pc = 206 264,8 AU = 30,856 78 x 1015 m (exactly).
LENGTH 172 PR [ISO 31-1:1992, 1-3.B.c]  
PERCENT % special (pure number) 1% = 0,01 x 1 (often omitted). PURE_NUMBER 179 PR [ISO 31-0:1992, 2.3.3]  
PPB_MASS_FRACTION none mass fraction (of B) The mass of B divided by the mass of the mixture.
1 x 10-9 kg/kg (exactly).
MASS_FRACTION 181 PR [ISO 31-8:1992, 8-12.a] [ISO 31-0:1992, 2.3.3]
PPM_MASS_FRACTION none mass fraction (of B) The mass of B divided by the mass of the mixture.
1 x 10-6 kg/kg (exactly).
MASS_FRACTION 182 PR [ISO 31-8:1992, 8-12.a] [ISO 31-0:1992, 2.3.3]
PPT_MASS_FRACTION none mass fraction (of B) The mass of B divided by the mass of the mixture.
1 x 10-12 kg/kg (exactly).
MASS_FRACTION 183 PR [ISO 31-8:1992, 8-12.a] [ISO 31-0:1992, 2.3.3]
PPTH_MASS_FRACTION none mass fraction (of B) The mass of B divided by the mass of the mixture.
1 x 10-3 kg/kg (exactly).
MASS_FRACTION 184 PR [ISO 31-8:1992, 8-12.a] [ISO 31-0:1992, 2.3.3]
RAD rd absorbed dose of ionizing radiation For any ionizing radiation, the energy imparted to an element of irradiated matter divided by the mass of this element.
1 rad = 1 cGy = 10-2 Gy (exactly).
ABSORBED_DOSE 185 PR [ISO 31-10:1992, 10-51.a (remarks)] [ISO 1000:1992, Annex A, 10-51.2]
REM rem dose equivalent of ionizing radiation The product of D, Q and N, at the point of interest in tissue, where D is the absorbed dose, Q is the quality factor and N is the product of any other modifying factors.
1 rem = 1 cSv = 10-2 Sv (exactly).
DOSE_EQUIVALENT 190 PR [ISO 31-10:1992, 10-52.a (remarks)] [ISO 1000:1992, Annex A, 10-52]
ROENTGEN R exposure of ionizing radiation The total electric charge of the ions of the same sign produced when all the electrons (negative and positive) liberated by photons in an element of air are stopped in air, divided by the mass of that element.
1 R = 2,58 x 104 C/kg (exactly).
EXPOSURE 191 PR [ISO 31-10:1992, 10-58.a (remarks)] [ISO 1000:1992, Annex A, 10-58]
TON ton mass 1 ton (US) = 907,184 7 kg (exactly). MASS 217 PR [ISO 31-3:1992, 3-1.B.e]  
YEAR a time (annum) The time that elapses between two successive passages of the <SUN> through the vernal equinox.
1 year = 365,242 20 d = 31 556 926 s (approximately).
TIME 245 PR [ISO 31-1:1992, 1-7.B.a]