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, 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".