Unit symbols are case sensitive. The following are the units that are
distributed with the Loom 4.0 release. Each entry specifies the base
unit for the measure, and the other units that are defined. These units
can be composed to form any arbitrary combination.
The syntax for dimensioned numbers is to have the numeric value
immediately followed by the units expression, with no intervening
speaces. Measurement units are delimited by exponents or the period
symbol (".") The division slash "/" may appear once in a unit
specification. As an example, the following are three alternate ways of
specifying 12 square meters per second:
12m.m/s 12m2/s 12m2s-1
SUMMARY OF MEASURES. Base unit is the base unit for that measure. Kind
is either fundamental or derived. Derived units have a definition in
terms of other units.
Name Base Unit Kind
===================== ========= ===========
DISTANCE-MEASURE m Fundamental
AREA-MEASURE m2 Derived
VOLUME-MEASURE m3 Derived
TIME-MEASURE s Fundamental
SPEED-MEASURE m/s Derived
ACCELERATION-MEASURE m/s2 Derived
ANGLE-MEASURE deg Fundamental
MASS-MEASURE kg Fundamental
FORCE-MEASURE N Derived
PRESSURE-MEASURE Pa Derived
DENSITY-MEASURE kg/m3 Derived
POWER-MEASURE W Derived
WORK-OR-TORQUE-MEASURE J Derived
REVOLUTION-MEASURE deg/s Derived
FREQUENCY-MEASURE Hz Derived
ELECTRIC-CURRENT-MEASURE A Fundamental
ELECTRIC-CHARGE-MEASURE C Derived
ELECTRIC-POTENTIAL-MEASURE V Derived
ELECTRIC-RESISTANCE-MEASURE ohm Derived
CAPACITANCE-MEASURE F Derived
INDUCTANCE-MEASURE H Derived
MAGNETIC-FLUX-MEASURE Wb Derived
MAGNETIC-FLUX-DENSITY-MEASURE T Derived
LUMINOUS-INTENSITY-MEASURE Cd Fundamental
ILLUMINANCE-MEASURE lux Derived
DATA-MEASURE bit Fundamental
TEMPERATURE-MEASURE K Fundamental
SCALAR-MEASURE Fundamental
FULL SPECIFICATION OF MEASURES. This table lists the measures, their
base units and definitions, and the units that have been defined for use
by users. The unit definitions will include the name and sometimes
other notes about the units available. The only areas where things get
a little tricky is with the Data-measure and the Temperature-Measure.
Although the system is largely base on the SI system of measures, we
have added many non-SI units in order to make the package as useful as
possible. The choice of non-SI units does have a strong U.S. bias.
DISTANCE-MEASURE base unit: m (Meter)
units: nm (nanometer)
um (micrometer)
mm (millimeter)
cm (centimeter)
dm (decimeter)
km (kilometer)
angstrom
ang (angstrom)
in (inch, international) Standard U.S. measure
ft (foot, international) Standard U.S. measure
yd (yard, international) Standard U.S. measure
mile (mile, international Standard U.S. measure
miles (mile)
mi (mil)
NM (nautical mile) lower case already taken
nautmi (nautical mile)
fathom
furlong
pica (pica) computer, not printer's
point (point) computer, not printer's
pt (point)
AU (Astronomical Unit)
lightyear Derived from year and c
LY (light year)
parsec
AREA-MEASURE base unit: m2 (Square Meter)
:units (mm2 cm2 km2 Obvious derivations
in2 yd2 ft2 mile2 NM2
sqyd (square yard)
sqft (square foot)
sqin (square inch)
sqkm (square kilometer)
sqmile (square mile)
hectare
ha (hectare)
are
a (are)
acre
VOLUME-MEASURE base unit: m3 (Cubic meter)
:units liter
l (liter)
ml (millileter)
cc (cubic centimeter)
cl (centiliter)
dl (deciliter)
Hl (hektoliter)
cuft (cubic foot)
cuyd (cubic yard)
mm3 cm3 km3 Obvious derivations
in3 ft3 yd3 mile3 NM3
acrefeet (acre foot)
gallon (gallon, U.S.) Not Imperial
pint (pint, U.S.) Not Imperial
quart (quart, U.S.) Not Imperial
gal (gallon, U.S.) Not Imperial
qt (quart, U.S.) Not Imperial
floz (fluid ounce)
cup (cup)
tbl (tablespoon)
tsp (teaspoon)
barrel (barrel, petroleum)
bbl (barral)
Mbbl (million barrels) 10^6
Bbbl (billion barrels) 10^9, U.S. billion
BRT (Brutto register ton) Register ton
TIME-MEASURE base unit: s (second)
:units ns (nanosecond)
us (microsecond)
ms (millisecond)
min (minute) "m" is taken for meter
h (hour)
hr (hour)
day (day)
days
week (week)
weeks
fortnight
year (mean tropical year) 365.24219 days
years
decade
century
SPEED-MEASURE base unit: m/s (meters per second)
:units km/h
mph
kts
ft/s
knots
c ; Speed of Light ; NIST, MfM
ACCELERATION-MEASURE base unit: m/s2 (meters per second squared)
:units G (Gee) acceleration due to 1 gravity
This permits use of standard
gravitational acceleration as if
it were a unit.
ft/s2 (feet per second squared)
ANGLE-MEASURE base unit: deg (degree)
:units rad (radian)
minute (minute of arc)
sec (second of arc)
mil (mil of angle) There are 6400 mils in a circle
Notes: The Angle-Measure uses degrees as the fundamental unit rather
than the SI standard of radians. This was done to make
conversions between degrees and minutes and seconds exact,
since the conversion between radians and degrees involves the
use of the irrational number PI.
MASS-MEASURE base unit: kg (kilogram)
:units g (gram)
mg (milligram)
ug (microgram)
lbs (pounds, avoidupois)
lb (pounds, avoidupois)
oz (ounces, avoidupois)
gr (grain)
mton (metric ton)
tonne (metric ton)
tonshort (ton, U.S. short) 2000 lbs
longton (ton, U.S. long) 2240
stone (stone)
hwt (hundredweight)
slug (slug)
carat (carat) Jewelers
FORCE-MEASURE base unit: N (Newton) Definition: kg.m/s2
:units g.m/s2
kN (kilonewton)
kgf (kilogram of force)
lbf (pound of force)
dyne (dyne)
PRESSURE-MEASURE base unit: Pa (Pascal) Definition: kg/s2m
:units g/s2m
N/m2 (Newton per square meter)
hPa (hectopascal)
kPa (kilopascal)
atm (atmosphere) Normal sea level air pressure
inHg (inches of mercury)
torr (torr)
mmHg (millimeters of mercury)
psi (pounds per square inch)
bar (bar)
mbar (millibar)
DENSITY-MEASURE base unit: kg/m3 (kilograms per cubic meter)
:units g/m3 (grams per cubic meter)
g/cm3 (grams per cubic centimeter)
lbs/in3 (pounds per cubic inch)
POWER-MEASURE base unit: W (Watt) Definition: m2kg/s3
:units N.m/s (Newton-meter per second)
mW (milliwatt)
kW (kilowatt)
MW (megawatt)
GW (gigawatt)
hp (horsepower)
shp (shaft horsepower)
WORK-OR-TORQUE-MEASURE base unit: J (Joule) Definition: m2kg/s2
:units N.m (Newton-meter) Preferred unit for torque
ft.lbf (foot-pound) Note: pound-force, not mass
in.lbf (inch-pount) Note: pound-force, not mass
kJ (kilojoule)
MJ (megajoule)
GJ (gigajoule)
BTU (British Thermal Unit, international)
cal (calorie, international)
kcal (kilocalorie)
therm (therm) EC definition, not US
kWh (kilowatt-hour)
Notes: Torque has the same units as work, so we cannot distinguish
between them
BTU and calorie have several different values. We have chosen
to use the international BTU and calorie.
REVOLUTION-MEASURE base unit: deg/s (degrees per second)
:units rps (revolutions per second) 360deg/sec
rpm (revolutions per minute) 360deg/min
FREQUENCY-MEASURE base unit: Hz (Hertz) Definition: s-1
:units kHz (kilohertz)
MHz (megahertz)
GHz (gigahertz)
ELECTRIC-CURRENT-MEASURE base unit: A (Ampere)
:units mA (milliampere, milliamp)
ELECTRIC-CHARGE-MEASURE base unit: C (Coulomb) Definition: s.A
:units pC (picocoulomb)
ELECTRIC-POTENTIAL-MEASURE base unit: V (Volt) Definition: m2kg/s3A = W/A
:units mV (millivolt)
kV (kilovolt)
MV (megavolt)
ELECTRIC-RESISTANCE-MEASURE base unit: ohm (Ohm) Definition: m2kg/s3A2 = V/A
:units kohm (kiloohm)
Mohm (megaohm)
CAPACITANCE-MEASURE base unit: F (Farad) Definition: A2s4/m2kg = C/V
:units mF (millifarad)
uF (microfarad)
pF (picofarad)
INDUCTANCE-MEASURE base unit: H (Henry) Definition: m2kg/A2s2 = Wb/A
MAGNETIC-FLUX-MEASURE base unit: Wb (Weber) Definition: m2kg/s2A = V.s
MAGNETIC-FLUX-DENSITY-MEASURE base unit: T (Tesla) Definition: kg/s2A = Wb/m2
LUMINOUS-INTENSITY-MEASURE base unit: Cd (Candela)
:units lumen (lumen)
lm (lumen)
Notes: Also includes luminous flux, which has the same reduced units.
ILLUMINANCE-MEASURE base unit: lux Definition: Cd/m2
:units lx (lux)
DATA-MEASURE base unit: bit (one bit)
:units byte (byte) 8 bits
BASE 2 Multiples:
kibit (kibibit) 2^10 bits
Kibit (kibibit)
Mibit (mibibit) 2^20 bits
KiB (kibibyte) 2^10 bytes
kiB (kibibyte)
MiB (mebibyte) 2^20 bytes
GiB (gibibyte) 2^30 bytes
TiB (tebibyte) 2^40 bytes
BASE 10 Multiples:
kbit (kilobit) 10^3 bits
Mbit (megabit) 10^6 bits
kB (kilobyte) 10^3 bytes
MB (megabyte) 10^6 bytes
GB (gigabyte) 10^9 bytes
TB (terabyte) 10^12 bytes
Note: The standard metri prefixes should only be used for multiples
of 10. For binary multiples, other related prefixes need to
be used. We use the prefixes for binary multiples that have
been adopted by the International Electrotechnical Commission
for use in information technology. See
http://physics.nist.gov/cuu/Units/binary.html
TEMPERATURE-MEASURE base unit: K (degree kelvin)
:units F (degree Fahrenheit)
C (degree Celsius) or Centigrade
R (degree Rankine) Fahrenheit counterpart to Kelvin
Note: The temperature measure differs from all the others in that it
is linked to a scale with different zero points for various
measures. That means that this measure can only be used for
describing the absolute temperature of items. It cannot
correctly be used in computations other than unit conversions
since it is tied to this outside scale.
In other words, don't add or subtract temperatures!
SCALAR-MEASURE
:units % (percent) 1/100
%% (promille) 1/1000
Note: All numbers without units belong to the scalar measure, even if
not specifically enumerated. This measure class is used to
allow the reader mechanism to support things like percent and
promille.
===============================================================================
References:
Guide for the Use of the International System of Units (SI)
U.S. Department of Commerce
National Institute of Standards and Technology (NIST)
NIST Special Publication 811, 1995 Edition
http://physics.nist.gov/Document/sp811.pdf
Richard A. Young and Thomas J. Glover
Measure for Measure
1996. ISBN 1-889796-00-X
(Blue Willow, Inc.; Littleton, Colorado, USA)
http://www.bluewillow.com