Annex 2 – Units recognised in international practice as determined by the President under Rule 49(2) (see F‑II, 4.13)
4. Units and names of units permitted in specialised fields only
Quantity |
Unit |
||
|---|---|---|---|
Name |
Symbol |
Value |
|
Vergency of optical systems |
dioptre |
1 dioptre = 1 m-1 |
|
Mass of precious stones |
metric carat |
1 metric carat = 2 x 10-4 kg |
|
Area of farmland and building land |
are |
a |
1 a = 102 m2 |
Mass per unit length of textile yarns and threads |
tex |
tex |
1 tex = 10-6 kg.m-1 |
Blood pressure and pressure of other body fluids |
millimetre of mercury |
mm Hg |
1 mm Hg = 133.322 Pa |
Pressure in the fields of plasma physics and semiconductors |
millimetre of mercury |
mm Hg |
1 mm Hg = 133.322387 Pa |
Torr |
Torr |
1 Torr = 133.322368 Pa |
|
Effective cross-sectional area |
Barn |
b |
1b = 10-28 m2 |
The prefixes and their symbols listed in F‑II, Annex 2, F-II, A 2, 1.3 may be used in conjunction with the above units and symbols, with the exception of the millimetre of mercury and its symbol. The multiple of 102 a is, however, called a "hectare".