Units
As described in the Units, the specification of units SHOULD follow the International System of Units (SI, abbreviated from the French Système international (d'unités)).
The CMIXF-12 convention for encoding units is RECOMMENDED to achieve maximum portability and limited variability of representation. If a CMIXF-12 representation of a unit is not possible, the unit can be declared as custom units and defined in an accompanying JSON file, as described in the units section. Earlier versions of the BIDS standard listed the following Unicode symbols, and these are still included for backwards compatibility:
Note that for the first two entries in this list, two characters are permissible for each, but the first character in each entry is preferred, per Unicode rules (see the section on "Duplicated Characters" on page 11 in the unicode report).
It is RECOMMENDED that units be CMIXF-12 compliant or among these five Unicode characters. Please note the appropriate upper- or lower- casing when using CMIXF-12.
For cases that are unspecified by this appendix or the units section, the CMIXF-12 convention applies.
You can use the cmixf Python package to check whether your formatting is compliant.
Examples for CMIXF-12 (including the five unicode symbols mentioned above):
-
Different formatting of "micro Volts":
- RECOMMENDED:
uV
orµV
- NOT RECOMMENDED:
microV
,µvolt
or1e-6V
- RECOMMENDED:
-
Combinations of units:
- RECOMMENDED:
V/us
for the Slew rate - NOT RECOMMENDED:
volts per microsecond
- RECOMMENDED:
Unit table
Unit name | Unit symbol | Quantity name |
---|---|---|
meter | m | length |
kilogram | kg | mass |
liter | L | volume |
second | s | time |
ampere | A | electric current |
kelvin | K | thermodynamic temperature |
mole | mol | amount of substance |
candela | cd | luminous intensity |
radian | rad | angle |
steradian | sr | solid angle |
hertz | Hz | frequency |
newton | N | force, weight |
pascal | Pa | pressure, stress |
joule | J | energy, work, heat |
watt | W | power, radiant flux |
coulomb | C | electric charge or quantity of electricity |
volt | V | voltage (electrical potential), emf |
farad | F | capacitance |
ohm | Ohm | resistance, impedance, reactance |
siemens | S | electrical conductance |
weber | Wb | magnetic flux |
tesla | T | magnetic flux density |
henry | H | inductance |
degree Celsius | oC | temperature relative to 273.15 K |
lumen | lm | luminous flux |
lux | lx | illuminance |
becquerel | Bq | radioactivity (decays per unit time) |
gray | Gy | absorbed dose (of ionizing radiation) |
sievert | Sv | equivalent dose (of ionizing radiation) |
katal | kat | catalytic activity |
Prefixes
Multiples
Prefix name | Prefix symbol | Factor |
---|---|---|
deca | da | 101 |
hecto | h | 102 |
kilo | k | 103 |
mega | M | 106 |
giga | G | 109 |
tera | T | 1012 |
peta | P | 1015 |
exa | E | 1018 |
zetta | Z | 1021 |
yotta | Y | 1024 |
Submultiples
Prefix name | Prefix symbol | Factor |
---|---|---|
deci | d | 10-1 |
centi | c | 10-2 |
milli | m | 10-3 |
micro | u | 10-6 |
nano | n | 10-9 |
pico | p | 10-12 |
femto | f | 10-15 |
atto | a | 10-18 |
zepto | z | 10-21 |
yocto | y | 10-24 |