"pi ratio of circumference to diameter "c speed of light "e charge on an electron "g acceleration of gravity "force same as g "mole Avogadros number "water pressure per unit height of water "mercury pressure per unit height of mercury "au astronomical unit
The unit pound is a unit of mass. Compound names are run together so pound force is a unit of force. The unit ounce is also a unit of mass. The fluid ounce is floz. British units that differ from their US counterparts are prefixed with br, and currency is prefixed with its country name: belgiumfranc, britainpound. When searching for a unit, if the specified string does not appear exactly as a unit name, then units will try to remove a trailing s or a trailing es and check again for a match.
To find out what units are available read the standard units file. If you want to add your own units you can supply your own file. A unit is specified on a single line by giving its name and an equivalence. Be careful to define new units in terms of old ones so that a reduction leads to the primitive units which are marked with ! characters. The units program will not detect infinite loops that could be caused by careless unit definitions. Comments in the unit definition file begin with a / character at the beginning of a line.
Prefixes are defined in the same was as standard units, but with a trailing dash at the end of the prefix name. If a unit is not found even after removing trailing s or es, then it will be checked against the list of prefixes. Prefixes will be removed until a legal base unit is identified.
Here is an example of a short units file that defines some basic units.
"m !a! "sec !b! "micro- 1e-6 "minute 60 sec "hour 60 min "inch 0.0254 m "ft 12 inches "mile 5280 ft