-- | View the source code for this declaration to see what units and prefixes
-- are defined by default.
--
-- This string holds the definitions for units and prefixes. Base units are
-- defined by the name of the unit, the name of the base in brackets, and any
-- aliases for the unit after that, all separated by equal signs: @meter =
-- [length] = m@. Prefixes are defined by placing a dash after all identifiers,
-- and providing a value for the prefix: @milli- = 1e-3 = m-@. Other units are
-- defined by using /previously defined units/ in an expression: @minute = 60 *
-- second = min@.
--
-- The reason these definitions aren't placed in a text file is so you don't
-- have to operate your whole program in the IO monad. Users can copy this file
-- into their source and modify definitions, or simply add a few definitions to
-- the end of this string.
--
-- These definitions are taken almost verbatim from the Pint unit conversion
-- library for the Python programming language. Check them out on
-- <https://github.com/hgrecco/pint GitHub>.
defaultDefString :: String
defaultDefString = unlines [

  -- decimal prefixes
  "yocto- = 1e-24 = y-"
  ,"zepto- = 1e-21 = z-"
  ,"atto- =  1e-18 = a-"
  ,"femto- = 1e-15 = f-"
  ,"pico- =  1e-12 = p-"
  ,"nano- =  1e-9  = n-"
  ,"micro- = 1e-6  = u-"
  ,"milli- = 1e-3  = m-"
  ,"centi- = 1e-2  = c-"
  ,"deci- =  1e-1  = d-"
  ,"deca- =  1e+1  = da-"
  ,"hecto- = 1e2   = h-"
  ,"kilo- =  1e3   = k-"
  ,"mega- =  1e6   = M-"
  ,"giga- =  1e9   = G-"
  ,"tera- =  1e12  = T-"
  ,"peta- =  1e15  = P-"
  ,"exa- =   1e18  = E-"
  ,"zetta- = 1e21  = Z-"
  ,"yotta- = 1e24  = Y-"

   -- binary_prefixes
  ,"kibi- = 2**10 = Ki-"
  ,"mebi- = 2**20 = Mi-"
  ,"gibi- = 2**30 = Gi-"
  ,"tebi- = 2**40 = Ti-"
  ,"pebi- = 2**50 = Pi-"
  ,"exbi- = 2**60 = Ei-"
  ,"zebi- = 2**70 = Zi-"
  ,"yobi- = 2**80 = Yi-"

   -- reference
  ,"meter = [length] = m = metre"
  ,"second = [time] = s = sec"
  ,"ampere = [current] = A = amp"
  ,"candela = [luminosity] = cd = candle"
  ,"gram = [mass] = g"
  ,"mole = [substance] = mol"
  --,"degK = [temperature]; offset: 0 = K = kelvin"
  ,"radian = [] = rad"
  ,"bit = []"
  ,"count = []"

  ,"pi = 3.14159265359"
  ,"gstandard_gravity = 9.806650 * meter / second ** 2 = g_0 = g_n = gravity"
  ,"speed_of_light = 299792458 * meter / second = c"

   -- acceleration
   -- [acceleration] = [length] / [time] ** 2

   -- Angle
  ,"turn = 2 * pi * radian = revolution = cycle = circle"
  ,"degree = pi / 180 * radian = deg = arcdeg = arcdegree = angular_degree"
  ,"arcminute = arcdeg / 60 = arcmin = arc_minute = angular_minute"
  ,"arcsecond = arcmin / 60 =  arcsec = arc_second = angular_second"
  ,"steradian = radian ** 2 = sr"

    -- Time
  ,"minute = 60 * second = min"
  ,"hour = 60 * minute = h = hr"
  ,"day = 24 * hour"
  ,"week = 7 * day"
  ,"fortnight = 2 * week"
  ,"year = 31556925.9747 * second"
  ,"month = year/12"
  ,"shake = 1e-8 * second"
  ,"sidereal_day = day / 1.00273790935079524"
  ,"sidereal_hour = sidereal_day/24"
  ,"sidereal_minute = sidereal_hour/60"
  ,"sidereal_second =sidereal_minute/60"
  ,"sidereal_year = 366.25636042 * sidereal_day"
  ,"sidereal_month = 27.321661 * sidereal_day"
  ,"tropical_month = 27.321661 * day"
  ,"synodic_month = 29.530589 * day = lunar_month"
  ,"common_year = 365 * day"
  ,"leap_year = 366 * day"
  ,"julian_year = 365.25 * day"
  ,"gregorian_year = 365.2425 * day"
  ,"millenium = 1000 * year = millenia = milenia = milenium"
  ,"eon = 1e9 * year"
  ,"work_year = 2056 * hour"
  ,"work_month = work_year/12"

   -- Length
  ,"angstrom = 1e-10 * meter"
  ,"inch = 2.54 * centimeter = international_inch = inches = international_inches = in"
  ,"foot = 12 * inch = international_foot = ft = feet = international_foot = international_feet"
  ,"mile = 5280 * foot = mi = international_mile"
  ,"yard = 3 * feet = yd = international_yard"
  ,"mil = inch / 1000 = thou"
  ,"parsec = 3.08568025e16 * meter = pc"
  ,"light_year = speed_of_light * julian_year = ly = lightyear"
  ,"astronomical_unit = 149597870691 * meter = au"
  ,"nautical_mile = 1.852e3 * meter = nmi"
  ,"printers_point = 127 * millimeter / 360 = point"
  ,"printers_pica = 12 * printers_point = pica"
  ,"US_survey_foot = 1200 * meter / 3937"
  ,"US_survey_yard =  3 * US_survey_foot"
  ,"US_survey_mile = 5280 * US_survey_foot = US_statute_mile"
  ,"rod = 16.5 * US_survey_foot = pole = perch"
  ,"furlong = 660 * US_survey_foot"
  ,"fathom = 6 * US_survey_foot"
  ,"chain = 66 * US_survey_foot"
  ,"barleycorn = inch / 3"
  ,"arpentlin = 191.835 * feet"
  ,"kayser = 1 / centimeter = wavenumber"


   -- Mass
  ,"ounce = 28.349523125 * gram = oz = avoirdupois_ounce"
  ,"dram = oz / 16 = dr = avoirdupois_dram"
  ,"pound = 0.45359237 * kilogram = lb = avoirdupois_pound"
  ,"stone = 14 * lb = st"
  ,"carat = 200 * milligram"
  ,"grain = 64.79891 * milligram = gr"
  ,"long_hundredweight = 112 * lb"
  ,"short_hundredweight = 100 * lb"
  ,"metric_ton = 1000 * kilogram = t = tonne"
  ,"pennyweight = 24 * gram = dwt"
  ,"slug = 14.59390 * kilogram"
  ,"troy_ounce = 480 * gram = toz = apounce = apothecary_ounce"
  ,"troy_pound = 12 * toz = tlb = appound = apothecary_pound"
  ,"drachm = 60 * gram = apdram = apothecary_dram"
  ,"atomic_mass_unit = 1.660538782e-27 * kilogram =  u = amu = dalton = Da"
  ,"scruple = 20 * gram"
  ,"bag = 94 * lb"
  ,"ton = 2000 * lb = short_ton"

   -- Force
   --[force] = [mass] * [acceleration]
  ,"newton = kilogram * meter / second ** 2 = N"
  ,"dyne = gram * centimeter / second ** 2 = dyn"
  ,"force_kilogram = g_0 * kilogram = kgf = kilogram_force = pond"
  ,"force_gram = g_0 * gram = gf = gram_force"
  ,"force_ounce = g_0 * ounce = ozf = ounce_force"
  ,"force_pound = g_0 * lb = lbf = pound_force"
  ,"force_ton = 2000 * force_pound = ton_force"
  ,"poundal = lb * feet / second ** 2 = pdl"
  ,"kip = 1000*lbf"

   -- Area
   -- [area] = [length] ** 2
  ,"are = 100 * m**2"
  ,"barn = 1e-28 * m ** 2 = b"
  ,"cmil = 5.067075e-10 * m ** 2 = circular_mils"
  ,"darcy = 9.869233e-13 * m ** 2"
  ,"acre = 4046.8564224 * m ** 2 = international_acre"
  ,"US_survey_acre = 160 * rod ** 2"

   -- Energy
  ,"joule = newton * meter = J"
  ,"erg = dyne * centimeter"
  ,"btu = 1.05505585262e3 * joule = Btu = BTU = british_thermal_unit"
  ,"eV = 1.60217653e-19 * J = electron_volt"
  ,"thm = 100000 * BTU = therm = EC_therm"
  ,"cal = 4.184 * joule = calorie = thermochemical_calorie"
  ,"international_steam_table_calorie = 4.1868 * joule"
  ,"ton_TNT = 4.184e9 * joule = tTNT"
  ,"US_therm = 1.054804e8 * joule"
  ,"E_h = 4.35974394e-18 * joule = hartree = hartree_energy"


  -- Power
  ,"watt = joule / second = W = volt_ampere = VA"
  ,"horsepower = 33000 * ft * lbf / min = hp = UK_horsepower = British_horsepower"
  ,"boiler_horsepower = 33475 * btu / hour"
  ,"metric_horsepower =  75 * force_kilogram * meter / second"
  ,"electric_horsepower = 746 * watt"
  ,"hydraulic_horsepower = 550 * feet * lbf / second"
  ,"refrigeration_ton = 12000 * btu / hour = ton_of_refrigeration"

  -- More Energy
  ,"watt_hour = watt * hour = Wh = watthour"

  -- EM
  ,"esu = 1 * erg**0.5 * centimeter**0.5 = statcoulombs = statC = franklin = Fr"
  ,"esu_per_second = 1 * esu / second = statampere"
  ,"ampere_turn = 1 * A"
  ,"gilbert = 10 / (4 * pi ) * ampere_turn = G"
  ,"coulomb = ampere * second = C"
  ,"volt = joule / coulomb = V"
  ,"farad = coulomb / volt = F"
  ,"ohm = volt / ampere"
  ,"siemens = ampere / volt = S = mho"
  ,"weber = volt * second = Wb"
  ,"tesla = weber / meter ** 2 = T"
  ,"henry = weber / ampere = H"
  ,"elementary_charge = 1.602176487e-19 * coulomb = e"
  ,"chemical_faraday = 9.64957e4 * coulomb"
  ,"physical_faraday = 9.65219e4 * coulomb"
  ,"faraday =  96485.3399 * coulomb = C12_faraday"
  ,"gamma = 1e-9 * tesla"
  ,"gauss = 1e-4 * tesla"
  ,"maxwell = 1e-8 * weber = mx"
  ,"oersted = 1000 / (4 * pi) * A / m = Oe"
  ,"statfarad = 1.112650e-12 * farad = statF = stF"
  ,"stathenry = 8.987554e11 * henry = statH = stH"
  ,"statmho = 1.112650e-12 * siemens = statS = stS"
  ,"statohm = 8.987554e11 * ohm"
  ,"statvolt = 2.997925e2 * volt = statV = stV"
  ,"unit_pole = 1.256637e-7 * weber"


   -- Frequency
  ,"hertz = 1 / second = Hz = rps"
  ,"revolutions_per_minute = revolution / minute = rpm"
  ,"counts_per_second = count / second = cps"

   -- Information
  ,"byte = 8 * bit = Bo = octet"
  ,"baud = bit / second = Bd = bps"

   -- Textile
  ,"denier =  gram / (9000 * meter)"
  ,"tex = gram/ (1000 * meter)"
  ,"dtex = decitex"

   -- Pressure
   -- [pressure] = [force] / [area]
  ,"Hg = gravity * 13.59510 * gram / centimeter ** 3 = mercury = conventional_mercury"
  ,"mercury_60F = gravity * 13.5568 * gram / centimeter ** 3"
  ,"H2O = gravity * 1000 * kilogram / meter ** 3 = h2o = water = conventional_water"
  ,"water_4C = gravity * 999.972 * kilogram / meter ** 3 = water_39F"
  ,"water_60F = gravity * 999.001 * kilogram / m ** 3"
  ,"pascal = newton / meter ** 2 = Pa"
  ,"bar = 100000 * pascal"
  ,"atmosphere = 101325 * pascal = atm = standard_atmosphere"
  ,"technical_atmosphere = kilogram * gravity / centimeter ** 2 = at"
  ,"torr = atm / 760"
  ,"psi = pound * gravity / inch ** 2 = pound_force_per_square_inch"
  ,"ksi = kip / inch ** 2 = kip_per_square_inch"
  ,"barye = 0.1 * newton / meter ** 2 = barie = barad = barrie = baryd = Ba"
  ,"mmHg = millimeter * Hg = mm_Hg = millimeter_Hg = millimeter_Hg_0C"
  ,"cmHg = centimeter * Hg = cm_Hg = centimeter_Hg"
  ,"inHg = inch * Hg = in_Hg = inch_Hg = inch_Hg_32F"
  ,"inch_Hg_60F = inch * mercury_60F"
  ,"inch_H2O_39F = inch * water_39F"
  ,"inch_H2O_60F = inch * water_60F"
  ,"footH2O = ft * water"
  ,"cmH2O = centimeter * water"
  ,"foot_H2O = ft * water = ftH2O"
  ,"standard_liter_per_minute = 1.68875 * Pa * m ** 3 / s = slpm = slm"


   -- Radiation
  ,"Bq = Hz = becquerel"
  ,"curie = 3.7e10 * Bq = Ci"
  ,"rutherford = 1e6*Bq = rd = Rd"
  ,"Gy = joule / kilogram = gray = Sv = sievert"
  ,"rem = 1e-2 * sievert"
  ,"rads = 1e-2 * gray"
  ,"roentgen = 2.58e-4 * coulomb / kilogram = R"

   -- Velocity
   -- [speed] = [length] / [time]
  ,"knot = nautical_mile / hour = kt = knot_international = international_knot = nautical_miles_per_hour"
  ,"mph = mile / hour = MPH"
  ,"kph = kilometer / hour = KPH"

   -- Viscosity
   -- [viscosity] = [pressure] * [time]
  ,"poise = 1e-1 * Pa * second = P"
  ,"stokes = 1e-4 * meter ** 2 / second = St"
  ,"rhe = 10 / (Pa * s)"

   -- Volume
   -- [volume] = [length] ** 3
  ,"liter = 1e-3 * m ** 3 = l = L = litre"
  ,"cc = centimeter ** 3 = cubic_centimeter"
  ,"stere = meter ** 3"
  ,"gross_register_ton = 100 * foot ** 3 = register_ton = GRT"
  ,"acre_foot = acre * foot = acre_feet"
  ,"board_foot = foot ** 2 * inch = FBM"
  ,"bushel = 2150.42 * inch ** 3 = bu = US_bushel"
  ,"dry_gallon = bushel / 8 = US_dry_gallon"
  ,"dry_quart = dry_gallon / 4 = US_dry_quart"
  ,"dry_pint = dry_quart / 2 = US_dry_pint"
  ,"gallon = 231 * inch ** 3 = liquid_gallon = US_liquid_gallon"
  ,"quart = gallon / 4 = liquid_quart = US_liquid_quart"
  ,"pint = quart / 2 = pt = liquid_pint = US_liquid_pint"
  ,"cup = pint / 2 = liquid_cup = US_liquid_cup"
  ,"gill = cup / 2 = liquid_gill = US_liquid_gill"
  ,"floz = gill / 4 = fluid_ounce = US_fluid_ounce = US_liquid_ounce"
  ,"imperial_bushel = 36.36872 * liter = UK_bushel"
  ,"imperial_gallon = imperial_bushel / 8 = UK_gallon"
  ,"imperial_quart = imperial_gallon / 4 = UK_quart"
  ,"imperial_pint = imperial_quart / 2 = UK_pint"
  ,"imperial_cup = imperial_pint / 2 = UK_cup"
  ,"imperial_gill = imperial_cup / 2 = UK_gill"
  ,"imperial_floz = imperial_gill / 5 = UK_fluid_ounce = imperial_fluid_ounce"
  ,"barrel = 42 * gallon = bbl"
  ,"tablespoon = floz / 2 = tbsp = Tbsp = Tblsp = tblsp = tbs = Tbl"
  ,"teaspoon = tablespoon / 3 = tsp"
  ,"peck = bushel / 4 = pk"
  ,"fluid_dram = floz / 8 = fldr = fluidram"
  ,"firkin = barrel / 4"
   ]
defaultDefString :: String
defaultDefString = unlines [

  -- decimal prefixes
  "yocto- = 1e-24 = y-"
  ,"zepto- = 1e-21 = z-"
  ,"atto- =  1e-18 = a-"
  ,"femto- = 1e-15 = f-"
  ,"pico- =  1e-12 = p-"
  ,"nano- =  1e-9  = n-"
  ,"micro- = 1e-6  = u-"
  ,"milli- = 1e-3  = m-"
  ,"centi- = 1e-2  = c-"
  ,"deci- =  1e-1  = d-"
  ,"deca- =  1e+1  = da-"
  ,"hecto- = 1e2   = h-"
  ,"kilo- =  1e3   = k-"
  ,"mega- =  1e6   = M-"
  ,"giga- =  1e9   = G-"
  ,"tera- =  1e12  = T-"
  ,"peta- =  1e15  = P-"
  ,"exa- =   1e18  = E-"
  ,"zetta- = 1e21  = Z-"
  ,"yotta- = 1e24  = Y-"

   -- binary_prefixes
  ,"kibi- = 2**10 = Ki-"
  ,"mebi- = 2**20 = Mi-"
  ,"gibi- = 2**30 = Gi-"
  ,"tebi- = 2**40 = Ti-"
  ,"pebi- = 2**50 = Pi-"
  ,"exbi- = 2**60 = Ei-"
  ,"zebi- = 2**70 = Zi-"
  ,"yobi- = 2**80 = Yi-"

   -- reference
  ,"meter = [length] = m = metre"
  ,"second = [time] = s = sec"
  ,"ampere = [current] = A = amp"
  ,"candela = [luminosity] = cd = candle"
  ,"gram = [mass] = g"
  ,"mole = [substance] = mol"
  --,"degK = [temperature]; offset: 0 = K = kelvin"
  ,"radian = [] = rad"
  ,"bit = []"
  ,"count = []"

  ,"pi = 3.14159265359"
  ,"gstandard_gravity = 9.806650 * meter / second ** 2 = g_0 = g_n = gravity"
  ,"speed_of_light = 299792458 * meter / second = c"

   -- acceleration
   -- [acceleration] = [length] / [time] ** 2

   -- Angle
  ,"turn = 2 * pi * radian = revolution = cycle = circle"
  ,"degree = pi / 180 * radian = deg = arcdeg = arcdegree = angular_degree"
  ,"arcminute = arcdeg / 60 = arcmin = arc_minute = angular_minute"
  ,"arcsecond = arcmin / 60 =  arcsec = arc_second = angular_second"
  ,"steradian = radian ** 2 = sr"

    -- Time
  ,"minute = 60 * second = min"
  ,"hour = 60 * minute = h = hr"
  ,"day = 24 * hour"
  ,"week = 7 * day"
  ,"fortnight = 2 * week"
  ,"year = 31556925.9747 * second"
  ,"month = year/12"
  ,"shake = 1e-8 * second"
  ,"sidereal_day = day / 1.00273790935079524"
  ,"sidereal_hour = sidereal_day/24"
  ,"sidereal_minute = sidereal_hour/60"
  ,"sidereal_second =sidereal_minute/60"
  ,"sidereal_year = 366.25636042 * sidereal_day"
  ,"sidereal_month = 27.321661 * sidereal_day"
  ,"tropical_month = 27.321661 * day"
  ,"synodic_month = 29.530589 * day = lunar_month"
  ,"common_year = 365 * day"
  ,"leap_year = 366 * day"
  ,"julian_year = 365.25 * day"
  ,"gregorian_year = 365.2425 * day"
  ,"millenium = 1000 * year = millenia = milenia = milenium"
  ,"eon = 1e9 * year"
  ,"work_year = 2056 * hour"
  ,"work_month = work_year/12"

   -- Length
  ,"angstrom = 1e-10 * meter"
  ,"inch = 2.54 * centimeter = international_inch = inches = international_inches = in"
  ,"foot = 12 * inch = international_foot = ft = feet = international_foot = international_feet"
  ,"mile = 5280 * foot = mi = international_mile"
  ,"yard = 3 * feet = yd = international_yard"
  ,"mil = inch / 1000 = thou"
  ,"parsec = 3.08568025e16 * meter = pc"
  ,"light_year = speed_of_light * julian_year = ly = lightyear"
  ,"astronomical_unit = 149597870691 * meter = au"
  ,"nautical_mile = 1.852e3 * meter = nmi"
  ,"printers_point = 127 * millimeter / 360 = point"
  ,"printers_pica = 12 * printers_point = pica"
  ,"US_survey_foot = 1200 * meter / 3937"
  ,"US_survey_yard =  3 * US_survey_foot"
  ,"US_survey_mile = 5280 * US_survey_foot = US_statute_mile"
  ,"rod = 16.5 * US_survey_foot = pole = perch"
  ,"furlong = 660 * US_survey_foot"
  ,"fathom = 6 * US_survey_foot"
  ,"chain = 66 * US_survey_foot"
  ,"barleycorn = inch / 3"
  ,"arpentlin = 191.835 * feet"
  ,"kayser = 1 / centimeter = wavenumber"


   -- Mass
  ,"ounce = 28.349523125 * gram = oz = avoirdupois_ounce"
  ,"dram = oz / 16 = dr = avoirdupois_dram"
  ,"pound = 0.45359237 * kilogram = lb = avoirdupois_pound"
  ,"stone = 14 * lb = st"
  ,"carat = 200 * milligram"
  ,"grain = 64.79891 * milligram = gr"
  ,"long_hundredweight = 112 * lb"
  ,"short_hundredweight = 100 * lb"
  ,"metric_ton = 1000 * kilogram = t = tonne"
  ,"pennyweight = 24 * gram = dwt"
  ,"slug = 14.59390 * kilogram"
  ,"troy_ounce = 480 * gram = toz = apounce = apothecary_ounce"
  ,"troy_pound = 12 * toz = tlb = appound = apothecary_pound"
  ,"drachm = 60 * gram = apdram = apothecary_dram"
  ,"atomic_mass_unit = 1.660538782e-27 * kilogram =  u = amu = dalton = Da"
  ,"scruple = 20 * gram"
  ,"bag = 94 * lb"
  ,"ton = 2000 * lb = short_ton"

   -- Force
   --[force] = [mass] * [acceleration]
  ,"newton = kilogram * meter / second ** 2 = N"
  ,"dyne = gram * centimeter / second ** 2 = dyn"
  ,"force_kilogram = g_0 * kilogram = kgf = kilogram_force = pond"
  ,"force_gram = g_0 * gram = gf = gram_force"
  ,"force_ounce = g_0 * ounce = ozf = ounce_force"
  ,"force_pound = g_0 * lb = lbf = pound_force"
  ,"force_ton = 2000 * force_pound = ton_force"
  ,"poundal = lb * feet / second ** 2 = pdl"
  ,"kip = 1000*lbf"

   -- Area
   -- [area] = [length] ** 2
  ,"are = 100 * m**2"
  ,"barn = 1e-28 * m ** 2 = b"
  ,"cmil = 5.067075e-10 * m ** 2 = circular_mils"
  ,"darcy = 9.869233e-13 * m ** 2"
  ,"acre = 4046.8564224 * m ** 2 = international_acre"
  ,"US_survey_acre = 160 * rod ** 2"

   -- Energy
  ,"joule = newton * meter = J"
  ,"erg = dyne * centimeter"
  ,"btu = 1.05505585262e3 * joule = Btu = BTU = british_thermal_unit"
  ,"eV = 1.60217653e-19 * J = electron_volt"
  ,"thm = 100000 * BTU = therm = EC_therm"
  ,"cal = 4.184 * joule = calorie = thermochemical_calorie"
  ,"international_steam_table_calorie = 4.1868 * joule"
  ,"ton_TNT = 4.184e9 * joule = tTNT"
  ,"US_therm = 1.054804e8 * joule"
  ,"E_h = 4.35974394e-18 * joule = hartree = hartree_energy"


  -- Power
  ,"watt = joule / second = W = volt_ampere = VA"
  ,"horsepower = 33000 * ft * lbf / min = hp = UK_horsepower = British_horsepower"
  ,"boiler_horsepower = 33475 * btu / hour"
  ,"metric_horsepower =  75 * force_kilogram * meter / second"
  ,"electric_horsepower = 746 * watt"
  ,"hydraulic_horsepower = 550 * feet * lbf / second"
  ,"refrigeration_ton = 12000 * btu / hour = ton_of_refrigeration"

  -- More Energy
  ,"watt_hour = watt * hour = Wh = watthour"

  -- EM
  ,"esu = 1 * erg**0.5 * centimeter**0.5 = statcoulombs = statC = franklin = Fr"
  ,"esu_per_second = 1 * esu / second = statampere"
  ,"ampere_turn = 1 * A"
  ,"gilbert = 10 / (4 * pi ) * ampere_turn = G"
  ,"coulomb = ampere * second = C"
  ,"volt = joule / coulomb = V"
  ,"farad = coulomb / volt = F"
  ,"ohm = volt / ampere"
  ,"siemens = ampere / volt = S = mho"
  ,"weber = volt * second = Wb"
  ,"tesla = weber / meter ** 2 = T"
  ,"henry = weber / ampere = H"
  ,"elementary_charge = 1.602176487e-19 * coulomb = e"
  ,"chemical_faraday = 9.64957e4 * coulomb"
  ,"physical_faraday = 9.65219e4 * coulomb"
  ,"faraday =  96485.3399 * coulomb = C12_faraday"
  ,"gamma = 1e-9 * tesla"
  ,"gauss = 1e-4 * tesla"
  ,"maxwell = 1e-8 * weber = mx"
  ,"oersted = 1000 / (4 * pi) * A / m = Oe"
  ,"statfarad = 1.112650e-12 * farad = statF = stF"
  ,"stathenry = 8.987554e11 * henry = statH = stH"
  ,"statmho = 1.112650e-12 * siemens = statS = stS"
  ,"statohm = 8.987554e11 * ohm"
  ,"statvolt = 2.997925e2 * volt = statV = stV"
  ,"unit_pole = 1.256637e-7 * weber"


   -- Frequency
  ,"hertz = 1 / second = Hz = rps"
  ,"revolutions_per_minute = revolution / minute = rpm"
  ,"counts_per_second = count / second = cps"

   -- Information
  ,"byte = 8 * bit = Bo = octet"
  ,"baud = bit / second = Bd = bps"

   -- Textile
  ,"denier =  gram / (9000 * meter)"
  ,"tex = gram/ (1000 * meter)"
  ,"dtex = decitex"

   -- Pressure
   -- [pressure] = [force] / [area]
  ,"Hg = gravity * 13.59510 * gram / centimeter ** 3 = mercury = conventional_mercury"
  ,"mercury_60F = gravity * 13.5568 * gram / centimeter ** 3"
  ,"H2O = gravity * 1000 * kilogram / meter ** 3 = h2o = water = conventional_water"
  ,"water_4C = gravity * 999.972 * kilogram / meter ** 3 = water_39F"
  ,"water_60F = gravity * 999.001 * kilogram / m ** 3"
  ,"pascal = newton / meter ** 2 = Pa"
  ,"bar = 100000 * pascal"
  ,"atmosphere = 101325 * pascal = atm = standard_atmosphere"
  ,"technical_atmosphere = kilogram * gravity / centimeter ** 2 = at"
  ,"torr = atm / 760"
  ,"psi = pound * gravity / inch ** 2 = pound_force_per_square_inch"
  ,"ksi = kip / inch ** 2 = kip_per_square_inch"
  ,"barye = 0.1 * newton / meter ** 2 = barie = barad = barrie = baryd = Ba"
  ,"mmHg = millimeter * Hg = mm_Hg = millimeter_Hg = millimeter_Hg_0C"
  ,"cmHg = centimeter * Hg = cm_Hg = centimeter_Hg"
  ,"inHg = inch * Hg = in_Hg = inch_Hg = inch_Hg_32F"
  ,"inch_Hg_60F = inch * mercury_60F"
  ,"inch_H2O_39F = inch * water_39F"
  ,"inch_H2O_60F = inch * water_60F"
  ,"footH2O = ft * water"
  ,"cmH2O = centimeter * water"
  ,"foot_H2O = ft * water = ftH2O"
  ,"standard_liter_per_minute = 1.68875 * Pa * m ** 3 / s = slpm = slm"


   -- Radiation
  ,"Bq = Hz = becquerel"
  ,"curie = 3.7e10 * Bq = Ci"
  ,"rutherford = 1e6*Bq = rd = Rd"
  ,"Gy = joule / kilogram = gray = Sv = sievert"
  ,"rem = 1e-2 * sievert"
  ,"rads = 1e-2 * gray"
  ,"roentgen = 2.58e-4 * coulomb / kilogram = R"

   -- Velocity
   -- [speed] = [length] / [time]
  ,"knot = nautical_mile / hour = kt = knot_international = international_knot = nautical_miles_per_hour"
  ,"mph = mile / hour = MPH"
  ,"kph = kilometer / hour = KPH"

   -- Viscosity
   -- [viscosity] = [pressure] * [time]
  ,"poise = 1e-1 * Pa * second = P"
  ,"stokes = 1e-4 * meter ** 2 / second = St"
  ,"rhe = 10 / (Pa * s)"

   -- Volume
   -- [volume] = [length] ** 3
  ,"liter = 1e-3 * m ** 3 = l = L = litre"
  ,"cc = centimeter ** 3 = cubic_centimeter"
  ,"stere = meter ** 3"
  ,"gross_register_ton = 100 * foot ** 3 = register_ton = GRT"
  ,"acre_foot = acre * foot = acre_feet"
  ,"board_foot = foot ** 2 * inch = FBM"
  ,"bushel = 2150.42 * inch ** 3 = bu = US_bushel"
  ,"dry_gallon = bushel / 8 = US_dry_gallon"
  ,"dry_quart = dry_gallon / 4 = US_dry_quart"
  ,"dry_pint = dry_quart / 2 = US_dry_pint"
  ,"gallon = 231 * inch ** 3 = liquid_gallon = US_liquid_gallon"
  ,"quart = gallon / 4 = liquid_quart = US_liquid_quart"
  ,"pint = quart / 2 = pt = liquid_pint = US_liquid_pint"
  ,"cup = pint / 2 = liquid_cup = US_liquid_cup"
  ,"gill = cup / 2 = liquid_gill = US_liquid_gill"
  ,"floz = gill / 4 = fluid_ounce = US_fluid_ounce = US_liquid_ounce"
  ,"imperial_bushel = 36.36872 * liter = UK_bushel"
  ,"imperial_gallon = imperial_bushel / 8 = UK_gallon"
  ,"imperial_quart = imperial_gallon / 4 = UK_quart"
  ,"imperial_pint = imperial_quart / 2 = UK_pint"
  ,"imperial_cup = imperial_pint / 2 = UK_cup"
  ,"imperial_gill = imperial_cup / 2 = UK_gill"
  ,"imperial_floz = imperial_gill / 5 = UK_fluid_ounce = imperial_fluid_ounce"
  ,"barrel = 42 * gallon = bbl"
  ,"tablespoon = floz / 2 = tbsp = Tbsp = Tblsp = tblsp = tbs = Tbl"
  ,"teaspoon = tablespoon / 3 = tsp"
  ,"peck = bushel / 4 = pk"
  ,"fluid_dram = floz / 8 = fldr = fluidram"
  ,"firkin = barrel / 4"
   ]
defaultDefString = unlines [

  -- decimal prefixes
  "yocto- = 1e-24 = y-"
  ,"zepto- = 1e-21 = z-"
  ,"atto- =  1e-18 = a-"
  ,"femto- = 1e-15 = f-"
  ,"pico- =  1e-12 = p-"
  ,"nano- =  1e-9  = n-"
  ,"micro- = 1e-6  = u-"
  ,"milli- = 1e-3  = m-"
  ,"centi- = 1e-2  = c-"
  ,"deci- =  1e-1  = d-"
  ,"deca- =  1e+1  = da-"
  ,"hecto- = 1e2   = h-"
  ,"kilo- =  1e3   = k-"
  ,"mega- =  1e6   = M-"
  ,"giga- =  1e9   = G-"
  ,"tera- =  1e12  = T-"
  ,"peta- =  1e15  = P-"
  ,"exa- =   1e18  = E-"
  ,"zetta- = 1e21  = Z-"
  ,"yotta- = 1e24  = Y-"

   -- binary_prefixes
  ,"kibi- = 2**10 = Ki-"
  ,"mebi- = 2**20 = Mi-"
  ,"gibi- = 2**30 = Gi-"
  ,"tebi- = 2**40 = Ti-"
  ,"pebi- = 2**50 = Pi-"
  ,"exbi- = 2**60 = Ei-"
  ,"zebi- = 2**70 = Zi-"
  ,"yobi- = 2**80 = Yi-"

   -- reference
  ,"meter = [length] = m = metre"
  ,"second = [time] = s = sec"
  ,"ampere = [current] = A = amp"
  ,"candela = [luminosity] = cd = candle"
  ,"gram = [mass] = g"
  ,"mole = [substance] = mol"
  --,"degK = [temperature]; offset: 0 = K = kelvin"
  ,"radian = [] = rad"
  ,"bit = []"
  ,"count = []"

  ,"pi = 3.14159265359"
  ,"gstandard_gravity = 9.806650 * meter / second ** 2 = g_0 = g_n = gravity"
  ,"speed_of_light = 299792458 * meter / second = c"

   -- acceleration
   -- [acceleration] = [length] / [time] ** 2

   -- Angle
  ,"turn = 2 * pi * radian = revolution = cycle = circle"
  ,"degree = pi / 180 * radian = deg = arcdeg = arcdegree = angular_degree"
  ,"arcminute = arcdeg / 60 = arcmin = arc_minute = angular_minute"
  ,"arcsecond = arcmin / 60 =  arcsec = arc_second = angular_second"
  ,"steradian = radian ** 2 = sr"

    -- Time
  ,"minute = 60 * second = min"
  ,"hour = 60 * minute = h = hr"
  ,"day = 24 * hour"
  ,"week = 7 * day"
  ,"fortnight = 2 * week"
  ,"year = 31556925.9747 * second"
  ,"month = year/12"
  ,"shake = 1e-8 * second"
  ,"sidereal_day = day / 1.00273790935079524"
  ,"sidereal_hour = sidereal_day/24"
  ,"sidereal_minute = sidereal_hour/60"
  ,"sidereal_second =sidereal_minute/60"
  ,"sidereal_year = 366.25636042 * sidereal_day"
  ,"sidereal_month = 27.321661 * sidereal_day"
  ,"tropical_month = 27.321661 * day"
  ,"synodic_month = 29.530589 * day = lunar_month"
  ,"common_year = 365 * day"
  ,"leap_year = 366 * day"
  ,"julian_year = 365.25 * day"
  ,"gregorian_year = 365.2425 * day"
  ,"millenium = 1000 * year = millenia = milenia = milenium"
  ,"eon = 1e9 * year"
  ,"work_year = 2056 * hour"
  ,"work_month = work_year/12"

   -- Length
  ,"angstrom = 1e-10 * meter"
  ,"inch = 2.54 * centimeter = international_inch = inches = international_inches = in"
  ,"foot = 12 * inch = international_foot = ft = feet = international_foot = international_feet"
  ,"mile = 5280 * foot = mi = international_mile"
  ,"yard = 3 * feet = yd = international_yard"
  ,"mil = inch / 1000 = thou"
  ,"parsec = 3.08568025e16 * meter = pc"
  ,"light_year = speed_of_light * julian_year = ly = lightyear"
  ,"astronomical_unit = 149597870691 * meter = au"
  ,"nautical_mile = 1.852e3 * meter = nmi"
  ,"printers_point = 127 * millimeter / 360 = point"
  ,"printers_pica = 12 * printers_point = pica"
  ,"US_survey_foot = 1200 * meter / 3937"
  ,"US_survey_yard =  3 * US_survey_foot"
  ,"US_survey_mile = 5280 * US_survey_foot = US_statute_mile"
  ,"rod = 16.5 * US_survey_foot = pole = perch"
  ,"furlong = 660 * US_survey_foot"
  ,"fathom = 6 * US_survey_foot"
  ,"chain = 66 * US_survey_foot"
  ,"barleycorn = inch / 3"
  ,"arpentlin = 191.835 * feet"
  ,"kayser = 1 / centimeter = wavenumber"


   -- Mass
  ,"ounce = 28.349523125 * gram = oz = avoirdupois_ounce"
  ,"dram = oz / 16 = dr = avoirdupois_dram"
  ,"pound = 0.45359237 * kilogram = lb = avoirdupois_pound"
  ,"stone = 14 * lb = st"
  ,"carat = 200 * milligram"
  ,"grain = 64.79891 * milligram = gr"
  ,"long_hundredweight = 112 * lb"
  ,"short_hundredweight = 100 * lb"
  ,"metric_ton = 1000 * kilogram = t = tonne"
  ,"pennyweight = 24 * gram = dwt"
  ,"slug = 14.59390 * kilogram"
  ,"troy_ounce = 480 * gram = toz = apounce = apothecary_ounce"
  ,"troy_pound = 12 * toz = tlb = appound = apothecary_pound"
  ,"drachm = 60 * gram = apdram = apothecary_dram"
  ,"atomic_mass_unit = 1.660538782e-27 * kilogram =  u = amu = dalton = Da"
  ,"scruple = 20 * gram"
  ,"bag = 94 * lb"
  ,"ton = 2000 * lb = short_ton"

   -- Force
   --[force] = [mass] * [acceleration]
  ,"newton = kilogram * meter / second ** 2 = N"
  ,"dyne = gram * centimeter / second ** 2 = dyn"
  ,"force_kilogram = g_0 * kilogram = kgf = kilogram_force = pond"
  ,"force_gram = g_0 * gram = gf = gram_force"
  ,"force_ounce = g_0 * ounce = ozf = ounce_force"
  ,"force_pound = g_0 * lb = lbf = pound_force"
  ,"force_ton = 2000 * force_pound = ton_force"
  ,"poundal = lb * feet / second ** 2 = pdl"
  ,"kip = 1000*lbf"

   -- Area
   -- [area] = [length] ** 2
  ,"are = 100 * m**2"
  ,"barn = 1e-28 * m ** 2 = b"
  ,"cmil = 5.067075e-10 * m ** 2 = circular_mils"
  ,"darcy = 9.869233e-13 * m ** 2"
  ,"acre = 4046.8564224 * m ** 2 = international_acre"
  ,"US_survey_acre = 160 * rod ** 2"

   -- Energy
  ,"joule = newton * meter = J"
  ,"erg = dyne * centimeter"
  ,"btu = 1.05505585262e3 * joule = Btu = BTU = british_thermal_unit"
  ,"eV = 1.60217653e-19 * J = electron_volt"
  ,"thm = 100000 * BTU = therm = EC_therm"
  ,"cal = 4.184 * joule = calorie = thermochemical_calorie"
  ,"international_steam_table_calorie = 4.1868 * joule"
  ,"ton_TNT = 4.184e9 * joule = tTNT"
  ,"US_therm = 1.054804e8 * joule"
  ,"E_h = 4.35974394e-18 * joule = hartree = hartree_energy"


  -- Power
  ,"watt = joule / second = W = volt_ampere = VA"
  ,"horsepower = 33000 * ft * lbf / min = hp = UK_horsepower = British_horsepower"
  ,"boiler_horsepower = 33475 * btu / hour"
  ,"metric_horsepower =  75 * force_kilogram * meter / second"
  ,"electric_horsepower = 746 * watt"
  ,"hydraulic_horsepower = 550 * feet * lbf / second"
  ,"refrigeration_ton = 12000 * btu / hour = ton_of_refrigeration"

  -- More Energy
  ,"watt_hour = watt * hour = Wh = watthour"

  -- EM
  ,"esu = 1 * erg**0.5 * centimeter**0.5 = statcoulombs = statC = franklin = Fr"
  ,"esu_per_second = 1 * esu / second = statampere"
  ,"ampere_turn = 1 * A"
  ,"gilbert = 10 / (4 * pi ) * ampere_turn = G"
  ,"coulomb = ampere * second = C"
  ,"volt = joule / coulomb = V"
  ,"farad = coulomb / volt = F"
  ,"ohm = volt / ampere"
  ,"siemens = ampere / volt = S = mho"
  ,"weber = volt * second = Wb"
  ,"tesla = weber / meter ** 2 = T"
  ,"henry = weber / ampere = H"
  ,"elementary_charge = 1.602176487e-19 * coulomb = e"
  ,"chemical_faraday = 9.64957e4 * coulomb"
  ,"physical_faraday = 9.65219e4 * coulomb"
  ,"faraday =  96485.3399 * coulomb = C12_faraday"
  ,"gamma = 1e-9 * tesla"
  ,"gauss = 1e-4 * tesla"
  ,"maxwell = 1e-8 * weber = mx"
  ,"oersted = 1000 / (4 * pi) * A / m = Oe"
  ,"statfarad = 1.112650e-12 * farad = statF = stF"
  ,"stathenry = 8.987554e11 * henry = statH = stH"
  ,"statmho = 1.112650e-12 * siemens = statS = stS"
  ,"statohm = 8.987554e11 * ohm"
  ,"statvolt = 2.997925e2 * volt = statV = stV"
  ,"unit_pole = 1.256637e-7 * weber"


   -- Frequency
  ,"hertz = 1 / second = Hz = rps"
  ,"revolutions_per_minute = revolution / minute = rpm"
  ,"counts_per_second = count / second = cps"

   -- Information
  ,"byte = 8 * bit = Bo = octet"
  ,"baud = bit / second = Bd = bps"

   -- Textile
  ,"denier =  gram / (9000 * meter)"
  ,"tex = gram/ (1000 * meter)"
  ,"dtex = decitex"

   -- Pressure
   -- [pressure] = [force] / [area]
  ,"Hg = gravity * 13.59510 * gram / centimeter ** 3 = mercury = conventional_mercury"
  ,"mercury_60F = gravity * 13.5568 * gram / centimeter ** 3"
  ,"H2O = gravity * 1000 * kilogram / meter ** 3 = h2o = water = conventional_water"
  ,"water_4C = gravity * 999.972 * kilogram / meter ** 3 = water_39F"
  ,"water_60F = gravity * 999.001 * kilogram / m ** 3"
  ,"pascal = newton / meter ** 2 = Pa"
  ,"bar = 100000 * pascal"
  ,"atmosphere = 101325 * pascal = atm = standard_atmosphere"
  ,"technical_atmosphere = kilogram * gravity / centimeter ** 2 = at"
  ,"torr = atm / 760"
  ,"psi = pound * gravity / inch ** 2 = pound_force_per_square_inch"
  ,"ksi = kip / inch ** 2 = kip_per_square_inch"
  ,"barye = 0.1 * newton / meter ** 2 = barie = barad = barrie = baryd = Ba"
  ,"mmHg = millimeter * Hg = mm_Hg = millimeter_Hg = millimeter_Hg_0C"
  ,"cmHg = centimeter * Hg = cm_Hg = centimeter_Hg"
  ,"inHg = inch * Hg = in_Hg = inch_Hg = inch_Hg_32F"
  ,"inch_Hg_60F = inch * mercury_60F"
  ,"inch_H2O_39F = inch * water_39F"
  ,"inch_H2O_60F = inch * water_60F"
  ,"footH2O = ft * water"
  ,"cmH2O = centimeter * water"
  ,"foot_H2O = ft * water = ftH2O"
  ,"standard_liter_per_minute = 1.68875 * Pa * m ** 3 / s = slpm = slm"


   -- Radiation
  ,"Bq = Hz = becquerel"
  ,"curie = 3.7e10 * Bq = Ci"
  ,"rutherford = 1e6*Bq = rd = Rd"
  ,"Gy = joule / kilogram = gray = Sv = sievert"
  ,"rem = 1e-2 * sievert"
  ,"rads = 1e-2 * gray"
  ,"roentgen = 2.58e-4 * coulomb / kilogram = R"

   -- Velocity
   -- [speed] = [length] / [time]
  ,"knot = nautical_mile / hour = kt = knot_international = international_knot = nautical_miles_per_hour"
  ,"mph = mile / hour = MPH"
  ,"kph = kilometer / hour = KPH"

   -- Viscosity
   -- [viscosity] = [pressure] * [time]
  ,"poise = 1e-1 * Pa * second = P"
  ,"stokes = 1e-4 * meter ** 2 / second = St"
  ,"rhe = 10 / (Pa * s)"

   -- Volume
   -- [volume] = [length] ** 3
  ,"liter = 1e-3 * m ** 3 = l = L = litre"
  ,"cc = centimeter ** 3 = cubic_centimeter"
  ,"stere = meter ** 3"
  ,"gross_register_ton = 100 * foot ** 3 = register_ton = GRT"
  ,"acre_foot = acre * foot = acre_feet"
  ,"board_foot = foot ** 2 * inch = FBM"
  ,"bushel = 2150.42 * inch ** 3 = bu = US_bushel"
  ,"dry_gallon = bushel / 8 = US_dry_gallon"
  ,"dry_quart = dry_gallon / 4 = US_dry_quart"
  ,"dry_pint = dry_quart / 2 = US_dry_pint"
  ,"gallon = 231 * inch ** 3 = liquid_gallon = US_liquid_gallon"
  ,"quart = gallon / 4 = liquid_quart = US_liquid_quart"
  ,"pint = quart / 2 = pt = liquid_pint = US_liquid_pint"
  ,"cup = pint / 2 = liquid_cup = US_liquid_cup"
  ,"gill = cup / 2 = liquid_gill = US_liquid_gill"
  ,"floz = gill / 4 = fluid_ounce = US_fluid_ounce = US_liquid_ounce"
  ,"imperial_bushel = 36.36872 * liter = UK_bushel"
  ,"imperial_gallon = imperial_bushel / 8 = UK_gallon"
  ,"imperial_quart = imperial_gallon / 4 = UK_quart"
  ,"imperial_pint = imperial_quart / 2 = UK_pint"
  ,"imperial_cup = imperial_pint / 2 = UK_cup"
  ,"imperial_gill = imperial_cup / 2 = UK_gill"
  ,"imperial_floz = imperial_gill / 5 = UK_fluid_ounce = imperial_fluid_ounce"
  ,"barrel = 42 * gallon = bbl"
  ,"tablespoon = floz / 2 = tbsp = Tbsp = Tblsp = tblsp = tbs = Tbl"
  ,"teaspoon = tablespoon / 3 = tsp"
  ,"peck = bushel / 4 = pk"
  ,"fluid_dram = floz / 8 = fldr = fluidram"
  ,"firkin = barrel / 4"
   ]