diff --git a/Kernel/dimensions.wl b/Kernel/dimensions.wl
index f3d415b..4977d27 100644
--- a/Kernel/dimensions.wl
+++ b/Kernel/dimensions.wl
@@ -98,8 +98,8 @@ Measure /: Subtract[a_,Measure[v_,d1,u_]] := Measure[a-v,d1,u]
 Measure /: Times[Measure[v1_,d1_,u_],Measure[v2_,d2_,u_]] := Measure[v1*v2,d1*d2,u]
 Measure /: Divide[Measure[v1_,d1_,u_],Measure[v2_,d2_,u_]] := Measure[v1/v2,d1/d2,u]
 Measure /: Power[Measure[v_,d_,u_],b_] := Measure[v^b,d^b,u]
-Measure /: Plus[Measure[v1_,d1_,u_],Measure[v2_,d2_,u_]] := Measure[v1+v2,d1+d2,u]
-Measure /: Subtract[Measure[v1_,d1_,u_],Measure[v2_,d2_,u_]] := Measure[v1-v2,d1-d2,u]
+Measure /: Plus[Measure[v1_,d_,u_],Measure[v2_,d_,u_]] := Measure[v1+v2,d,u]
+Measure /: Subtract[Measure[v1_,d_,u_],Measure[v2_,d_,u_]] := Measure[v1-v2,d,u]
 Measure /: Sqrt[Measure[v_,d_,u_]] := Measure[Sqrt[v],Sqrt[d],u]
 
 Measure /: Equal[Measure[v_,USQ[l_,c_],u_],a_] := And[Total[l]==0,a==v*c]
diff --git a/Kernel/physics.wl b/Kernel/physics.wl
index 11e21d8..57a1fb1 100644
--- a/Kernel/physics.wl
+++ b/Kernel/physics.wl
@@ -131,7 +131,7 @@ AngularMomentum[u_UnitSystem, s_UnitSystem] := Unit[Momentum[u, s] Length[u, s]
 ForceOnsetRate[u_UnitSystem, s_UnitSystem] := Unit[Mass[u, s] Jerk[u, s]];
 MassPerArea[u_UnitSystem, s_UnitSystem] := Unit[Mass[u, s]/Area[u, s]];
 MassDensity[u_UnitSystem, s_UnitSystem] := Unit[Mass[u, s]/Volume[u, s]];
-SpecificWeight[u_UnitSystem, s_UnitSystem] := Unit[Pressure[u, s]/Speed[u, s]^2];
+SpecificWeight[u_UnitSystem, s_UnitSystem] := Unit[Force[u, s]/Volume[u, s]];
 SpecificVolume[u_UnitSystem, s_UnitSystem] := Unit[Volume[u, s]/Mass[u, s]];
 Action[u_UnitSystem, s_UnitSystem] := Unit[Energy[u, s] Time[u, s]];
 (*Stiffness[u_UnitSystem, s_UnitSystem] := Unit[Force[u, s]/Length[u, s]];*)
@@ -258,7 +258,7 @@ Map[(#[u_UnitSystem] := #[u, Universe[u]]) &, {CosmologicalConstant, AvogadroCon
 AvogadroConstant[u_UnitSystem, c_Coupling] := MolarMassConstant[u, c] ElectronRelativeAtomicMass[c]/ElectronMass[u, c];
 AtomicMassConstant[u_UnitSystem, c_Coupling] := ElectronMass[u, c]/ElectronRelativeAtomicMass[c];
 ProtonMass[u_UnitSystem, c_Coupling] := ProtonElectronMassRatio[c] ElectronMass[u, c];
-GaussianGravitationalConstant[u_UnitSystem, c_Couling] = Sqrt[GravitationalConstant[u,c]]
+GaussianGravitationalConstant[u_UnitSystem, c_Couling] = Measure[MM@Sqrt[GravitationalConstant[u,c]],dA/dT,"IAU"][u]
 EinsteinConstantSpeedOfLightSquared[u_UnitSystem, c_Coupling] := (2 Spat[u] GravitationalConstant[u, c])/SpeedOfLight[u, c]^2;
 EinsteinConstantSpeedOfLightToTheFourth[u_UnitSystem, c_Coupling] := (2 Spat[u] GravitationalConstant[u, c])/SpeedOfLight[u, c]^4;
 MolarGasConstant[u_UnitSystem, c_Coupling] := BoltzmannConstant[u, c] AvogadroConstant[u, c];
diff --git a/Kernel/standards.wl b/Kernel/standards.wl
index 71004c5..b78feb8 100644
--- a/Kernel/standards.wl
+++ b/Kernel/standards.wl
@@ -78,6 +78,13 @@ StandardUnits = <|
 "Hour" -> Measure[60^2,dT,"Metric"],
 "Day" -> Measure[1,dT,"IAU"],
 "RadarMile" -> Measure[2,dL,"Nautical"]/SpeedOfLight["Nautical"],
+"ips" -> Measure[1,dL/dT,"IPS"],
+"fps" -> Measure[1,dL/dT,"British"],
+"fpm" -> Measure[1,dL/dT,"British"],
+"ms" -> Measure[1,dL/dT,"Metric"],
+"kmh" -> Measure[1,dL/dT,"KKH"],
+"mph" -> Measure[1,dL/dT,"MPH"],
+"knot" -> Measure[1,dL/dT,"Nautical"],
 "Barn" -> Measure[10^-28,dL^2,"Metric"],
 "Hectare" -> Measure[Pre["hecto"] Pre["hecto"],dL^2,"Metric"],
 "Acre" -> Measure[2^-7/5,dL^2,"MPH"],
@@ -173,7 +180,8 @@ StandardUnits = <|
 "FootLambert" -> Measure[1/Pi,USQ[Luminance],"English"],
 "Bril" -> Measure[Pre["centi"] Pre["nano"]/Pi,USQ[Luminance],"Gauss"],
 "Hertz" -> Measure[1,d1/dT,"Metric"],
-"RPM" -> Measure[1/60,d1/dT,"Metric"],
+"APM" -> Measure[1/60,d1/dT,"Metric"],
+"RPM" -> Measure[Pi/30,d1/dT,"Metric"],
 "Galileo" -> Measure[1,USQ[SpecificForce],"Gauss"],
 "Eotvos" -> Measure[Pre["nano"],USQ[SpecificForce]/dL,"Gauss"],
 "Poise" -> Measure[1,USQ[DynamicViscosity],"Gauss"],
diff --git a/Project.toml b/Project.toml
index 066e040..115f841 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "UnitSystems"
 uuid = "3a241a3c-2137-41aa-af5e-1388e404ca09"
 authors = ["Michael Reed"]
-version = "0.3.4"
+version = "0.3.5"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/README.md b/README.md
index af8d036..4ce7c76 100644
--- a/README.md
+++ b/README.md
@@ -49,7 +49,7 @@ additional constants `molarmass`, `luminousefficacy`, `gravity`, `angle`, `turn`
 
 Physics constant documentation is at https://geophysics.crucialflow.com/dev/constants
 
-Standardized unit/derived quantities are `hyperfine`, `loschmidt`, `wienwavelength`, `wienfrequency`, `mechanicalheat`, `solarmass`, `jupitermass`, `earthmass`, `lunarmass`, `earthradius`, `greatcircle`, `radarmile`, `hubble`, `cosmological`, `radian`, `steradian`, `degree`, `gradian`, `arcminute`, `arcsecond`, `second`, `minute`, `hour`, `day`, `year`, `gaussianyear`, `siderealyear`, `angstrom`, `inch`, `foot`, `surveyfoot`, `yard`, `meter`, `earthmeter`, `mile`, `statutemile`, `meridianmile`, `admiraltymile`, `nauticalmile`, `lunardistance`, `astronomicalunit`, `lightyear`, `parsec`, `barn`, `hectare`, `acre`, `surveyacre`, `liter`, `gallon`, `quart`, `pint`, `cup`, `fluidounce`, `teaspoon`, `tablespoon`, `grain`, `gram`, `earthgram`, `kilogram`, `tonne`, `ton`, `pound`, `ounce`, `slug`, `slinch`, `hyl`, `dyne`, `newton`, `poundal`, `poundforce`, `kilopond`, `psi`, `pascal`, `bar`, `barye`, `technicalatmosphere`, `atmosphere`, `inchmercury`, `torr`, `electronvolt`, `erg`, `joule`, `footpound`, `calorie`, `kilocalorie`, `meancalorie`, `earthcalorie`, `thermalunit`, `gasgallon`, `tontnt`, `watt`, `horsepower`, `horsepowerwatt`, `horsepowermetric`, `electricalhorsepower`, `tonsrefrigeration`, `boilerhorsepower`, `coulomb`, `earthcoulomb`, `ampere`, `volt`, `henry`, `ohm`, `siemens`, `farad`, `weber`, `tesla`, `abcoulomb`, `abampere`, `abvolt`, `abhenry`, `abohm`, `abmho`, `abfarad`, `maxwell`, `gauss`, `oersted`, `gilbert`, `statcoulomb`, `statampere`, `statvolt`, `stathenry`, `statohm`, `statmho`, `statfarad`, `statweber`, `stattesla`, `kelvin`, `rankine`, `celsius`, `fahrenheit`, `sealevel`, `boiling`, `mole`, `earthmole`, `poundmole`, `slugmole`, `slinchmole`, `katal`, `amagat`, `lumen`, `candela`, `lux`, `phot`, `footcandle`, `nit`, `apostilb`, `stilb`, `lambert`, `footlambert`, `bril`, `neper`, `bel`, `decibel`, `hertz`, `rpm`, `kayser`, `diopter`, `bubnoff`, `gforce`, `galileo`, `eotvos`, `darcy`, `poise`, `reyn`, `stokes`, `rayl`, `mpge`, `langley`, `jansky`, `solarflux`, `curie`, `sievert`, `roentgen`, `rem`.
+Standardized unit/derived quantities are `hyperfine`, `loschmidt`, `wienwavelength`, `wienfrequency`, `mechanicalheat`, `solarmass`, `jupitermass`, `earthmass`, `lunarmass`, `earthradius`, `greatcircle`, `radarmile`, `hubble`, `cosmological`, `radian`, `steradian`, `degree`, `gradian`, `arcminute`, `arcsecond`, `second`, `minute`, `hour`, `day`, `gaussianmonth`, `siderealmonth`, `synodicmonth`, `year`, `gaussianyear`, `siderealyear`, `jovianyear`, `angstrom`, `inch`, `foot`, `surveyfoot`, `yard`, `meter`, `earthmeter`, `mile`, `statutemile`, `meridianmile`, `admiraltymile`, `nauticalmile`, `lunardistance`, `astronomicalunit`, `jupiterdistance`, `lightyear`, `parsec`, `bubnoff`, `ips`, `fps`, `fpm`, `ms`, `kmh`, `mph`, `knot`, `mps`, `barn`, `hectare`, `acre`, `surveyacre`, `liter`, `gallon`, `quart`, `pint`, `cup`, `fluidounce`, `teaspoon`, `tablespoon`, `grain`, `gram`, `earthgram`, `kilogram`, `tonne`, `ton`, `pound`, `ounce`, `slug`, `slinch`, `hyl`, `dyne`, `newton`, `poundal`, `poundforce`, `kilopond`, `psi`, `pascal`, `bar`, `barye`, `technicalatmosphere`, `atmosphere`, `inchmercury`, `torr`, `electronvolt`, `erg`, `joule`, `footpound`, `calorie`, `kilocalorie`, `meancalorie`, `earthcalorie`, `thermalunit`, `gasgallon`, `tontnt`, `watt`, `horsepower`, `horsepowerwatt`, `horsepowermetric`, `electricalhorsepower`, `tonsrefrigeration`, `boilerhorsepower`, `coulomb`, `earthcoulomb`, `ampere`, `volt`, `henry`, `ohm`, `siemens`, `farad`, `weber`, `tesla`, `abcoulomb`, `abampere`, `abvolt`, `abhenry`, `abohm`, `abmho`, `abfarad`, `maxwell`, `gauss`, `oersted`, `gilbert`, `statcoulomb`, `statampere`, `statvolt`, `stathenry`, `statohm`, `statmho`, `statfarad`, `statweber`, `stattesla`, `kelvin`, `rankine`, `celsius`, `fahrenheit`, `sealevel`, `boiling`, `mole`, `earthmole`, `poundmole`, `slugmole`, `slinchmole`, `katal`, `amagat`, `lumen`, `candela`, `lux`, `phot`, `footcandle`, `nit`, `apostilb`, `stilb`, `lambert`, `footlambert`, `bril`, `neper`, `bel`, `decibel`, `hertz`, `apm`, `rpm`, `kayser`, `diopter`, `gforce`, `galileo`, `eotvos`, `darcy`, `poise`, `reyn`, `stokes`, `rayl`, `mpge`, `langley`, `jansky`, `solarflux`, `curie`, `sievert`, `roentgen`, `rem`.
 
 Standard physics units are at https://geophysics.crucialflow.com/dev/units
 
diff --git a/src/UnitSystems.jl b/src/UnitSystems.jl
index ed4b1a9..5457cf3 100644
--- a/src/UnitSystems.jl
+++ b/src/UnitSystems.jl
@@ -24,10 +24,11 @@ const Constants = (:lightspeed,:planck,:planckreduced,:electronmass,:molarmass,:
 const Physics = (:turn,:spat,:atomicmass,:protonmass,:planckmass,:gravitation,:gaussgravitation,:einstein,:hartree,:rydberg,:bohr,:electronradius,:avogadro,:molargas,:stefan,:radiationdensity,:vacuumpermeability,:vacuumpermittivity,:electrostatic,:magnetostatic,:biotsavart,:elementarycharge,:faraday,:vacuumimpedance,:conductancequantum,:klitzing,:josephson,:magneticfluxquantum,:magneton)
 const Derived = (:hyperfine,:loschmidt,:wienwavelength,:wienfrequency,:mechanicalheat,:solarmass,:jupitermass,:earthmass,:lunarmass,:earthradius,:greatcircle,:radarmile,:hubble,:cosmological,
     :radian,:steradian,:degree,:gradian,:arcminute,:arcsecond,
-    :second,:minute,:hour,:day,:year,:gaussianyear,:siderealyear,
-    :angstrom,:inch,:foot,:surveyfoot,:yard,:meter,:earthmeter,:mile,:statutemile,:meridianmile,:admiraltymile,:nauticalmile,:lunardistance,:astronomicalunit,:lightyear,:parsec,
+    :second,:minute,:hour,:day,:gaussianmonth,:siderealmonth,:synodicmonth,:year,:gaussianyear,:siderealyear,:jovianyear,
+    :angstrom,:inch,:foot,:surveyfoot,:yard,:meter,:earthmeter,:mile,:statutemile,:meridianmile,:admiraltymile,:nauticalmile,:lunardistance,:astronomicalunit,:jupiterdistance,:lightyear,:parsec,
     :barn,:hectare,:acre,:surveyacre,
     :liter,:gallon,:quart,:pint,:cup,:fluidounce,:teaspoon,:tablespoon,
+    :bubnoff,:ips,:fps,:fpm,:ms,:kmh,:mph,:knot,:mps,
     :grain,:gram,:earthgram,:kilogram,:tonne,:ton,:pound,:ounce,:slug,:slinch,:hyl,
     :dyne,:newton,:poundal,:poundforce,:kilopond,
     :psi,:pascal,:bar,:barye,:technicalatmosphere,:atmosphere,:inchmercury,:torr,
@@ -38,8 +39,8 @@ const Derived = (:hyperfine,:loschmidt,:wienwavelength,:wienfrequency,:mechanica
     :statcoulomb,:statampere,:statvolt,:stathenry,:statohm,:statmho,:statfarad,:statweber,:stattesla,
     :kelvin,:rankine,:celsius,:fahrenheit,:sealevel,:boiling,:mole,:earthmole,:poundmole,:slugmole,:slinchmole,:katal,:amagat,
     :lumen,:candela,:lux,:phot,:footcandle,:nit,:apostilb,:stilb,:lambert,:footlambert,:bril,
-    :neper,:bel,:decibel,:hertz,:rpm,
-    :kayser,:diopter,:bubnoff,:gforce,:galileo,:eotvos,:darcy,:poise,:reyn,:stokes,:rayl,
+    :neper,:bel,:decibel,:hertz,:apm,:rpm,
+    :kayser,:diopter,:gforce,:galileo,:eotvos,:darcy,:poise,:reyn,:stokes,:rayl,
     :mpge,:langley,:jansky,:solarflux,:curie,:sievert,:roentgen,:rem)
 const Kinematic = (:solidangle,:time,:length,:area,:volume,:wavenumber,:angularwavenumber,:fuelefficiency,:numberdensity,:frequency,:angularfrequency,:frequencydrift,:speed,:acceleration,:jerk,:snap,:crackle,:pop,:volumeflow) #angle
 const Mechanical = (:inertia,:mass,:massflow,:lineardensity,:areadensity,:density,:specificweight,:specificvolume,:force,:specificforce,:gravityforce,:pressure,:compressibility,:viscosity,:diffusivity,:rotationalinertia,:impulse,:momentum,:angularmomentum,:yank,:energy,:specificenergy,:action,:fluence,:power,:powerdensity,:intensity,:spectralflux,:soundexposure,:impedance,:specificimpedance,:admittance,:compliance,:inertance)
@@ -314,7 +315,8 @@ const RK1990,KJ1990,Rᵤ2014 = Constant(25812.807),Constant(4.835979e14),Constan
 const RK2014,KJ2014 = Constant(25812.8074555),Constant(4.835978525e14)
 const GME,GMJ = Constant(398600441.8e6),Constant(1.26686534e17)
 const kG,H0,ΩΛ = Constant(3548.18761),Constant(67.66),Constant(0.6889)
-const aⱼ,au,LD = Constant(365.25),Constant(149597870.7e3),Constant(384402e3)
+const aⱼ,au = Constant(365.25),Constant(149597870.7e3)
+const LD,JD = Constant(384399e3),Constant(778479e6)
 const zetta,zepto = Constant(1e21),Constant(1e-21)
 const yotta,yocto = Constant(1e24),Constant(1e-24)
 const 𝟏,𝟐,𝟑,𝟓,𝟕,𝟏𝟎,𝟏𝟏,𝟏𝟗,𝟒𝟑,τ,α = Constant(1),Constant(2),Constant(3),Constant(5),Constant(7),Constant(10),Constant(11),Constant(19),Constant(43),Constant(2π),inv(αinv)
diff --git a/src/constant.jl b/src/constant.jl
index 4d3840d..c850c8a 100644
--- a/src/constant.jl
+++ b/src/constant.jl
@@ -40,6 +40,7 @@ Base.:/(a::Number,b::Constant) = a*inv(b)
 Base.:/(a::Constant,b::Number) = a*inv(b)
 Base.inv(a::Constant{D}) where D = Constant{inv(D)}()
 Base.sqrt(a::Constant{D}) where D = Constant{sqrt(D)}()
+Base.cbrt(a::Constant{D}) where D = Constant{cbrt(D)}()
 Base.log(x::Constant{D}) where D = Constant{log(D)}()
 Base.log2(x::Constant{D}) where D = Constant{log2(D)}()
 Base.log10(x::Constant{D}) where D = Constant{log10(D)}()
diff --git a/src/derived.jl b/src/derived.jl
index 97aff3b..26446db 100644
--- a/src/derived.jl
+++ b/src/derived.jl
@@ -21,8 +21,8 @@
 @pure arcminute(U::UnitSystem) = degree(U)/two(U)^2/three(U)/five(U)
 @pure arcsecond(U::UnitSystem) = arcminute(U)/two(U)^2/three(U)/five(U)
 
-@pure rpm(U::UnitSystem) = one(U)/minute(U)
-#@pure rpd(U::UnitSystem) = turn(U)/day(U)
+@pure apm(U::UnitSystem) = one(U)/minute(U)
+@pure rpm(U::UnitSystem) = turn(U)/minute(U)
 
 # time
 
@@ -52,7 +52,8 @@
 @pure nauticalmile(U::UnitSystem) = length(one(U),U,Nautical)
 #@pure navigationmile(U::UnitSystem) = greatcircle(U)/two(U)^5/three(U)^3/five(U)^2
 @pure astronomicalunit(U::UnitSystem) = length(𝟏,U,IAU)
-@pure lunardistance(U::UnitSystem) = length(LD,U,Metric)
+@pure lunardistance(U::UnitSystem) = length(𝟏,U,IAUE)
+@pure jupiterdistance(U::UnitSystem) = length(𝟏,U,IAUJ)
 @pure mile(U::UnitSystem) = length(two(U)^5*three(U)*five(U)*eleven(U),U,English)
 @pure admiraltymile(U::UnitSystem) = length(two(U)^6*five(U)*nineteen(U),U,English)
 @pure meridianmile(U::UnitSystem) = length(two(U)^4*five(U)^5/three(U)^3,U,Metric)
@@ -80,6 +81,18 @@
 @pure tablespoon(U::UnitSystem) = three(U)*teaspoon(U)
 #@pure oilbarrel(U::UnitSystem) = two(U)*three(U)*seven(U)*gallon(U)
 
+# speed
+
+@pure bubnoff(U::UnitSystem) = meter(U)/year(U)
+@pure ips(U::UnitSystem) = inch(U)/second(U)
+@pure fps(U::UnitSystem) = foot(U)/second(U)
+@pure fpm(U::UnitSystem) = foot(U)/minute(U)
+@pure ms(U::UnitSystem) = meter(U)/second(U)
+@pure kmh(U::UnitSystem) = kilo(U)*meter(U)/hour(U)
+@pure mph(U::UnitSystem) = mile(U)/hour(U)
+@pure knot(U::UnitSystem) = nauticalmile(U)/hour(U)
+@pure mps(U::UnitSystem) = mile(U)/second(U)
+
 # mass
 
 @pure grain(U::UnitSystem) = milli(U)*pound(U)/seven(U)
@@ -212,7 +225,6 @@
 @pure hertz(U::UnitSystem) = one(U)/second(U)
 @pure kayser(U::UnitSystem) = wavenumber(one(U),U,Gauss)
 @pure diopter(U::UnitSystem) = wavenumber(one(U),U,Metric)
-@pure bubnoff(U::UnitSystem) = meter(U)/year(U)
 @pure gforce(U::UnitSystem) = specificforce(one(U),U,English)
 @pure galileo(U::UnitSystem) = specificforce(one(U),U,Gauss)
 @pure eotvos(U::UnitSystem) = specificforce(nano(U),U,Gauss)/length(one(U),U,Gauss)
diff --git a/src/derivedocs.jl b/src/derivedocs.jl
index c03e580..13b6d55 100644
--- a/src/derivedocs.jl
+++ b/src/derivedocs.jl
@@ -428,7 +428,7 @@ $(astronomicalunit(Metric)/lightspeed(Metric))
 """ astronomicalunit, au
 
 @doc """
-$(unitext(:lunardistance,"length($LD,U,Metric)"))
+$(unitext(:lunardistance,"length(𝟏,U,IAUE)"))
 
 Standard distance between the Earth and the Moon (m or ft).
 ```Julia
@@ -443,6 +443,22 @@ $(lunardistance(Metric)/lightspeed(Metric))
 ```
 """ lunardistance, LD
 
+@doc """
+$(unitext(:jupiterdistance,"length(𝟏,U,IAUJ)"))
+
+Standard distance between the Sun and the planet Jupiter (m or ft).
+```Julia
+julia> jupiterdistance(Metric) # m
+$(jupiterdistance(Metric))
+
+julia> jupiterdistance(IAU) # au
+$(jupiterdistance(IAU))
+
+julia> jupiterdistance(Metric)/lightspeed(Metric) # s
+$(jupiterdistance(Metric)/lightspeed(Metric))
+```
+""" jupiterdistance, JD
+
 @doc """
 $(unitext(:mile,"length(𝟏,U,MPH)"))
 
@@ -735,6 +751,146 @@ $(tablespoon(IPS))
 ```
 """ tablespoon
 
+# speed
+
+@doc """
+$(unitext(:bubnoff,"meter(U)/year(U)"))
+
+Reference unit of erosion `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> bubnoff(CGS) # cm⋅s⁻¹
+$(bubnoff(CGS))
+
+julia> bubnoff(English) # ft⋅s⁻¹
+$(bubnoff(English))
+```
+""" bubnoff
+
+@doc """
+$(unitext(:ips,"inch(U)/second(U)"))
+
+Inch per second unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> ips(CGS) # cm⋅s⁻¹
+$(ips(CGS))
+
+julia> ips(English) # ft⋅s⁻¹
+$(ips(English))
+```
+""" ips
+
+@doc """
+$(unitext(:fps,"feet(U)/second(U)"))
+
+Feet per second unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> fps(Metric) # m⋅s⁻¹
+$(fps(Metric))
+
+julia> fps(KKH) # km⋅h⁻¹
+$(fps(KKH))
+
+julia> fps(MPH) # mi⋅h⁻¹
+$(fps(MPH))
+```
+""" fps
+
+@doc """
+$(unitext(:fpm,"feet(U)/minute(U)"))
+
+Feet per minute unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> fpm(CGS) # cm⋅s⁻¹
+$(fpm(CGS))
+
+julia> fpm(IPS) # in⋅s⁻¹
+$(fpm(IPS))
+
+julia> fpm(English) # ft⋅s⁻¹
+$(fpm(English))
+```
+""" fpm
+
+@doc """
+$(unitext(:ms,"meter(U)/second(U)"))
+
+Meters per second unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> ms(KKH) # km⋅h⁻¹
+$(ms(KKH))
+
+julia> ms(MPH) # mi⋅h⁻¹
+$(ms(MPH))
+
+julia> ms(Nautical) # nm⋅h⁻¹
+$(ms(Nautical))
+```
+""" ms
+
+@doc """
+$(unitext(:kmh,"kilo(U)*meter(U)/hour(U)"))
+
+Kilometers per hour unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> kmh(Metric) # m⋅s⁻¹
+$(kmh(Metric))
+
+julia> kmh(MPH) # mi⋅h⁻¹
+$(kmh(MPH))
+
+julia> kmh(Nautical) # nm⋅h⁻¹
+$(kmh(Nautical))
+```
+""" kmh
+
+@doc """
+$(unitext(:mph,"mile(U)/hour(U)"))
+
+Miles per hour unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> mph(Metric) # m⋅s⁻¹
+$(mph(Metric))
+
+julia> mph(KKH) # km⋅h⁻¹
+$(mph(KKH))
+
+julia> mph(Nautical) # nm⋅h⁻¹
+$(mph(Nautical))
+```
+""" mph
+
+@doc """
+$(unitext(:knot,"nauticalmile(U)/hour(U)"))
+
+Nautical miles per hour unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> knot(Metric) # m⋅s⁻¹
+$(knot(Metric))
+
+julia> knot(KKH) # km⋅h⁻¹
+$(knot(KKH))
+
+julia> knot(MPH) # mi⋅h⁻¹
+$(knot(MPH))
+```
+""" knot
+
+@doc """
+$(unitext(:mps,"mile(U)/second(U)"))
+
+Miles per second unit of `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
+```Julia
+julia> mps(KKH) # km⋅h⁻¹
+$(mps(KKH))
+
+julia> mps(MPH) # mi⋅h⁻¹
+$(mps(MPH))
+
+julia> mps(Nautical) # nm⋅h⁻¹
+$(mps(Nautical))
+```
+""" mps
+
 # mass
 
 @doc """
@@ -2417,9 +2573,22 @@ $(hertz(IAU))
 """ hertz
 
 @doc """
-$(unitext(:rpm,"𝟏/minute(U)"))
+$(unitext(:apm,"𝟏/minute(U)"))
+
+Actions per minute `apm` unit of `frequency` (s⁻¹).
+```Julia
+julia> apm(MetricEngineering) # s⁻¹
+$(apm(MetricEngineering))
+
+julia> apm(IAU) # D⁻¹
+$(apm(IAU))
+```
+""" apm
+
+@doc """
+$(unitext(:rpm,"turn(U)/minute(U)"))
 
-Engineering unit of `frequency` (s⁻¹).
+Revolutions per minute `rpm` unit of `angularfrequency` (s⁻¹).
 ```Julia
 julia> rpm(MetricEngineering) # rad⋅s⁻¹
 $(rpm(MetricEngineering))
@@ -2461,22 +2630,6 @@ $(diopter(English))
 ```
 """ diopter
 
-@doc """
-$(unitext(:bubnoff,"meter(U)/year(U)"))
-
-Reference unit of erosion `speed` (m⋅s⁻¹ or ft⋅s⁻¹).
-```Julia
-julia> bubnoff(Metric) # m⋅s⁻¹
-$(bubnoff(Metric))
-
-julia> bubnoff(CGS) # cm⋅s⁻¹
-$(bubnoff(CGS))
-
-julia> bubnoff(English) # ft⋅s⁻¹
-$(bubnoff(English))
-```
-""" bubnoff
-
 @doc """
 $(unitext(:gforce,"specificforce(𝟏,U,English)"))
 
diff --git a/src/initdata.jl b/src/initdata.jl
index c38e630..cf77db0 100644
--- a/src/initdata.jl
+++ b/src/initdata.jl
@@ -27,8 +27,7 @@ const lc,mc,ρΛ = 𝟐*sqrt(τ/ΛC),𝘤^2/(𝟐*sqrt(τ*ΛC*G)),ΛC*𝘤^4/(
 const lcq,mcq = sqrt.(sqrt.((𝘤*ħ/ρΛ,ρΛ*ħ^3/𝘤^5)))
 const tcq,em,mi = lcq*sqrt(mcq/sqrt(sqrt(ρΛ*(𝘤*ħ)^3))),sqrt(GME/g₀)*τ/𝟐^9/𝟓^7,𝟐^5*𝟑*𝟓*𝟏𝟏
 
-@pure sackurtetrode(P,T=𝟏) = sackurtetrode(SI2019,P,T)
-@pure sackurtetrode(U::UnitSystem,P=atm,T=𝟏) = normal(log(Constant(exp(5/2))*T*boltzmann(U)/P*sqrt(electronmass(U)/gravity(U)/electronunit(U)*boltzmann(U)*T/turn(U)/planckreduced(U)^2)^3))
+@pure sackurtetrode(U::UnitSystem,P=atm,T=𝟏,m=atomicmass(U)) = normal(log((Constant(exp(5/2))*boltzmann(U)*sqrt(boltzmann(U)/gravity(U)/turn(U)/planckreduced(U)^2)^3)*(T/P*sqrt(m*T)^3)))
 
 const Universe = Coupling(αG,α,μₑᵤ,μₚᵤ,ΩΛ)
 
@@ -108,8 +107,8 @@ const GravitationalSI2019 = Quantity(EntropySystem(SI2019,𝟏,𝟏,g₀))
 const GravitationalMetric = Quantity(EntropySystem(Metric,𝟏,𝟏,g₀))
 const GravitationalMeridian = Quantity(EntropySystem(Metric,𝟏,em,g₀*em^2,𝟏,τ/𝟐^6/𝟓^7*em/g₀,milli))
 const IAU☉ = Quantity(EntropySystem(Metric,DAY,au,GM☉/G))
-const IAUE = Quantity(EntropySystem(Metric,DAY,au,GME/G))
-const IAUJ = Quantity(EntropySystem(Metric,DAY,au,GMJ/G))
+const IAUE = Quantity(EntropySystem(Metric,DAY,LD,GME/G))
+const IAUJ = Quantity(EntropySystem(Metric,DAY,JD,GMJ/G))
 const MTS = Quantity(EntropySystem(Metric,𝟏,𝟏,kilo))
 const KKH = Quantity(EntropySystem(Metric,HOUR,kilo,𝟏))
 const MPH = Quantity(EntropySystem(FPS,HOUR,mi,𝟏))
diff --git a/src/kinematic.jl b/src/kinematic.jl
index a9317b6..19c0051 100644
--- a/src/kinematic.jl
+++ b/src/kinematic.jl
@@ -145,7 +145,7 @@ $(time(PlanckGauss,Metric))
 @pure yank(U::UnitSystem,S::UnitSystem) = unit(mass(U,S)*jerk(U,S))
 @pure areadensity(U::UnitSystem,S::UnitSystem) = unit(mass(U,S)/area(U,S))
 @pure density(U::UnitSystem,S::UnitSystem) = unit(mass(U,S)/volume(U,S))
-@pure specificweight(U::UnitSystem,S::UnitSystem) = unit(pressure(U,S)/speed(U,S)^2)
+@pure specificweight(U::UnitSystem,S::UnitSystem) = unit(force(U,S)/volume(U,S))
 @pure specificvolume(U::UnitSystem,S::UnitSystem) = unit(volume(U,S)/mass(U,S))
 @pure action(U::UnitSystem,S::UnitSystem) = unit(energy(U,S)*time(U,S))
 #@pure stiffness(U::UnitSystem,S::UnitSystem) = unit(force(U,S)/length(U,S))
diff --git a/src/kinematicdocs.jl b/src/kinematicdocs.jl
index 201ab42..3bad694 100644
--- a/src/kinematicdocs.jl
+++ b/src/kinematicdocs.jl
@@ -593,18 +593,18 @@ $(density(English,Metric))
 """ density
 
 @doc """
-$(convertext(:specificweight,"pressure(U,S)/speed(U,S)^2"))
+$(convertext(:specificweight,"force(U,S)/volume(U,S)"))
 
-Specific weight or `force` per `volume` or `density` (N⋅m⁻³), unit conversion factor.
+Specific weight or `force` per `volume` (N⋅m⁻³ or lb⋅ft⁻³), unit conversion factor.
 ```Julia
-julia> density(CGS,Metric) # N⋅cm³⋅dyn⁻¹⋅m⁻³
-$(density(CGS,Metric))
+julia> specificweight(CGS,Metric) # N⋅cm³⋅dyn⁻¹⋅m⁻³
+$(specificweight(CGS,Metric))
 
-julia> density(CGS,Brtish) # lb⋅cm³⋅dyn⁻¹⋅ft⁻³
-$(density(CGS,British))
+julia> specificweight(CGS,Brtish) # lb⋅cm³⋅dyn⁻¹⋅ft⁻³
+$(specificweight(CGS,British))
 
-julia> density(English,Metric) # N⋅ft³⋅lb⁻¹⋅m⁻³
-$(density(English,Metric))
+julia> specificweight(English,Metric) # N⋅ft³⋅lb⁻¹⋅m⁻³
+$(specificweight(English,Metric))
 ```
 """ specificweight
 
diff --git a/src/physics.jl b/src/physics.jl
index f4b3646..0b9cc56 100644
--- a/src/physics.jl
+++ b/src/physics.jl
@@ -15,7 +15,7 @@
 @pure avogadro(U::UnitSystem,C::Coupling=universe(U)) = molarmass(U,C)*electronunit(C)/electronmass(U,C)
 @pure atomicmass(U::UnitSystem,C::Coupling=universe(U)) = electronmass(U,C)/electronunit(C)
 @pure protonmass(U::UnitSystem,C::Coupling=universe(U)) = protonelectron(C)*electronmass(U,C)
-@pure gaussgravitation(U::UnitSystem,C::Coupling=universe(U)) = sqrt(gravitation(U,C))
+@pure gaussgravitation(U::UnitSystem,C::Coupling=universe(U)) = sqrt(normal(gravitation(IAU)))*radian(U)/day(U)
 @pure einstein(U::UnitSystem,C::Coupling=universe(U)) = two(U)*spat(U)*gravitation(U,C)/lightspeed(U,C)^4
 #@pure einstein2(U::UnitSystem,C::Coupling=universe(U)) = two(U)*spat(U)*gravitation(U,C)/lightspeed(U,C)^2
 @pure molargas(U::UnitSystem,C::Coupling=universe(U)) = boltzmann(U,C)*avogadro(U,C)
@@ -50,8 +50,12 @@
 @pure jupitermass(U::UnitSystem) = mass(GMJ/G,U,Metric)
 @pure lunarmass(U::UnitSystem) = earthmass(U)/μE☾
 @pure mechanicalheat(U::UnitSystem) = molargas(U)*normal(calorie(Metric)/molargas(Metric))
-@pure gaussianyear(U::UnitSystem) = (τ/k)*day(U)
-@pure siderealyear(U::UnitSystem) = gaussianyear(U)/√(solarmass(IAU)+earthmass(IAU)+lunarmass(IAU))
+@pure gaussianyear(U::UnitSystem) = turn(U)/gaussgravitation(U)
+@pure siderealyear(U::UnitSystem) = gaussianyear(U)/normal(sqrt(solarmass(IAU)+earthmass(IAU)+lunarmass(IAU)))
+@pure gaussianmonth(U::UnitSystem) = normal(turn(Metric)*sqrt(normal(lunardistance(Metric))^3/GME))*time(Metric,U)
+@pure siderealmonth(U::UnitSystem) = gaussianmonth(U)/normal(sqrt(earthmass(IAUE)+lunarmass(IAUE)))
+@pure synodicmonth(U::UnitSystem) = inv(inv(siderealmonth(U))-inv(siderealyear(U)))
+@pure jovianyear(U::UnitSystem) = day(U)*sqrt(normal(jupiterdistance(U)^3/solarmass(U)/gravitation(U)))*turn(U)/radian(U)/normal(sqrt(solarmass(IAU)+jupitermass(IAU)))
 
 include("derived.jl")
 
diff --git a/src/physicsdocs.jl b/src/physicsdocs.jl
index 11ca66a..fec6015 100644
--- a/src/physicsdocs.jl
+++ b/src/physicsdocs.jl
@@ -410,22 +410,6 @@ $(gravitation(PlanckGauss))
 ```
 """ gravitation, G, GG
 
-@doc """
-$(unitext(:gaussgravitation,"sqrt(lightspeed(U)*planckreduced(U))/planckmass(U)"))
-
-Gaussian  gravitational constant `k` of Newton's laws.
-```Julia
-julia> gaussgravitation(IAU)
-$(gaussgravitation(IAU))
-
-juila> gaussgravitation(Cosmological)
-$(gaussgravitation(Cosmological))
-
-julia> gaussgravitation(PlanckGauss)
-$(gaussgravitation(PlanckGauss))
-```
-""" gaussgravitation, k, kG
-
 @doc """
 $(unitext(:einstein,"𝟐*spat(U)*gravitation(U)/lightspeed(U)^4"))
 
@@ -988,6 +972,12 @@ Bohr radius of the hydrogen atom in its ground state `a₀` (m).
 ```Julia
 julia> bohr(Metric) # m
 $(bohr(Metric))
+
+julia> bohr(IPS) # in
+$(bohr(IPS))
+
+julia> bohr(Hartree) # a₀
+$(bohr(Hartree))
 ```
 """ bohr, a₀, a0
 #julia> bohr(Metric)/length(PlanckGauss) # ℓP
@@ -1278,9 +1268,25 @@ $(lunarmass(IAUJ))
 """ lunarmass
 
 @doc """
-$(unitext(:gaussianyear,"(τ/k)*day(U)"))
+$(unitext(:gaussgravitation,"sqrt(gravitation(U)*solarmass(U)/astronomicalunit(U)^3)"))
 
-Orbit `time` defined by `gaussgravitation(IAU)` constant `k` value for neglible `mass`.
+Gaussian  gravitational constant `k` of Newton's laws (Hz or rad⋅D⁻¹).
+```Julia
+julia> gaussgravitation(Metric)
+$(gaussgravitation(Metric))
+
+juila> gaussgravitation(MPH)
+$(gaussgravitation(MPH))
+
+julia> gaussgravitation(IAU)
+$(gaussgravitation(IAU))
+```
+""" gaussgravitation, k, kG
+
+@doc """
+$(unitext(:gaussianyear,"turn(U)/gaussgravitation(U)"))
+
+Orbit `time` defined by `gaussgravitation` constant `kG` for neglible `mass` satellite.
 ```Julia
 julia> gaussianyear(Metric) # s
 $(gaussianyear(Metric))
@@ -1296,7 +1302,7 @@ $(gaussianyear(IAU))
 @doc """
 $(unitext(:siderealyear,"gaussianyear(U)/√(𝟏+earthmass(IAU)+lunarmass(IAU))"))
 
-Orbit `time` defined by `gaussgravitation(IAU)` constant and the Earth system `mass`.
+Orbit `time` defined by `gaussgravitation` constant `kG` and the Earth-Moon system `mass`.
 ```Julia
 julia> siderealyear(Metric) # s
 $(siderealyear(Metric))
@@ -1309,6 +1315,70 @@ $(siderealyear(IAU))
 ```
 """ siderealyear
 
+@doc """
+$(unitext(:jovianyear,"τ*day(U)*√(jupiterdistance(U)^3/solarmass(U)/gravitation(U))/√(𝟏+jupitermass(IAU))"))
+
+Orbit `time` defined by `jupiterdistance` and the Sun-Jupiter system `mass`.
+```Julia
+julia> jovianyear(Metric) # s
+$(jovianyear(Metric))
+
+julia> jovianyear(MPH) # h
+$(jovianyear(MPH))
+
+julia> jovianyear(IAU) # D
+$(jovianyear(IAU))
+```
+""" jovianyear
+
+@doc """
+$(unitext(:gaussianmonth,"τ*sqrt(lunardistance(U)^3/earthmass(U)/gravitation(U))"))
+
+Orbit `time` defined by `lunardistance` and `earthmass` for neglible `mass` satellite.
+```Julia
+julia> gaussianmonth(Metric) # s
+$(gaussianmonth(Metric))
+
+julia> gaussianmonth(MPH) # h
+$(gaussianmonth(MPH))
+
+julia> gaussianmonth(IAU) # D
+$(gaussianmonth(IAU))
+```
+""" gaussianmonth
+
+@doc """
+$(unitext(:siderealmonth,"gaussianmonth(U)/√(𝟏+lunarmass(IAU))"))
+
+Orbit `time` defined by standard `lunardistance` and the Earth-Moon system `mass`.
+```Julia
+julia> siderealmonth(Metric) # s
+$(siderealmonth(Metric))
+
+julia> siderealmonth(MPH) # h
+$(siderealmonth(MPH))
+
+julia> siderealmonth(IAU) # D
+$(siderealmonth(IAU))
+```
+""" siderealmonth
+
+@doc """
+$(unitext(:synodicmonth,"𝟏/(𝟏/siderealmonth(U)-𝟏/siderealyear(U))"))
+
+Orbit `time` defined by `siderealmonth` and `siderealyear` of the Sun-Earth-Moon system.
+```Julia
+julia> synodicmonth(Metric) # s
+$(synodicmonth(Metric))
+
+julia> synodicmonth(MPH) # h
+$(synodicmonth(MPH))
+
+julia> synodicmonth(IAU) # D
+$(synodicmonth(IAU))
+```
+""" synodicmonth
+
 @doc """
 $(unitext(:earthradius,"sqrt(earthmass(U)*gravitation(U)/gforce(U))"))
 
@@ -1342,10 +1412,10 @@ $(greatcircle(IAU))
 """ greatcircle
 
 @doc """
-    sackurtetrode(P,T=𝟏) = log(Constant(exp(5/2))*T*kB/P*sqrt(mₑ/μₑᵤ*kB*T/τ/ħ^2)^3)
-    sackurtetrode(U::UnitSystem,P=atm,T=𝟏) = # Sackur-Tetrode formula
+    sackurtetrode(U::UnitSystem,P=atm,T=𝟏,m=mᵤ) = log(kB*T/P*sqrt(m*kB*T/τ/ħ^2)^3)+5/2
+    dimensionless : [𝟙], [𝟙], [𝟙], [𝟙], [𝟙]
 
-Entropy ratio of a monatomic ideal gas at pressure `P` and temperature `T` (dimensionless).
+Ideal gas entropy density for pressure `P`, temperature `T`, atomicmass `m` (dimensionless).
 ```Julia
 julia> sackurtetrode(Metric)
 $(sackurtetrode(Metric))
diff --git a/src/systems.jl b/src/systems.jl
index 4be18cb..15e0f14 100644
--- a/src/systems.jl
+++ b/src/systems.jl
@@ -96,7 +96,7 @@ Can be multiplied, added, subtracted, and so on.
 @doc """
     Metric = MetricSystem(milli,𝟐*τ/𝟏𝟎^7)
 
-Systeme International d'Unites (the SI units) adopted as the preferred `UnitSystem`.
+Standard `Metric` system based on exact `molarmass` and `vacuumpermeability`.
 
 ```Julia
 julia> boltzmann(Metric) # J⋅K⁻¹
@@ -125,7 +125,7 @@ $(luminousefficacy(Metric))
 @doc """
     SI2019 = MetricSystem(Mᵤ,μ₀)
 
-Systeme International d'Unites (the SI units) with `μ₀` for a tuned `charge` exactly.
+Systeme International d'Unites based on approximate `molarmass` and `vacuumpermeability`.
 
 ```Julia
 julia> boltzmann(SI2019) # J⋅K⁻¹
@@ -154,7 +154,7 @@ $(luminousefficacy(SI2019))
 @doc """
     MetricEngineering = MetricSystem(milli,𝟐*τ/𝟏𝟎^7,Rᵤ,g₀)
 
-Systeme International d'Unites (the SI units) based on kilogram and kilopond units.
+Standard `MetricEngineering` system based on kilogram and kilopond (kilogram-force) units.
 
 ```Julia
 julia> boltzmann(MetricEngineering) # kgf⋅m⋅K⁻¹
@@ -186,7 +186,7 @@ $(gravity(MetricEngineering))
 @doc """
     SI2019Engineering = MetricSystem(Mᵤ,μ₀,Rᵤ,g₀)
 
-Systeme International d'Unites (the SI units) based on kilogram and kilopond units.
+Systeme International d'Unites based on kilogram and kilopond (kilogram-force) units.
 
 ```Julia
 julia> boltzmann(SI2019Engineering) # kgf⋅m⋅K⁻¹
@@ -218,7 +218,7 @@ $(gravity(SI2019Engineering))
 @doc """
     SI1976 = MetricSystem(milli,𝟐*τ/𝟏𝟎^7,8.31432)
 
-Systeme International d'Unites (the SI units) with universal gas constant of `8.31432`.
+Reference `UnitSystem` with universal gas constant of `8.31432` from 1976 standard atmosphere.
 
 ```Julia
 julia> boltzmann(SI1976) # J⋅K⁻¹
@@ -247,7 +247,7 @@ $(luminousefficacy(SI1976))
 @doc """
     CODATA = ConventionalSystem(RK2014,KJ2014,Rᵤ2014)
 
-Metric `UnitSystem` based on Committee on Data of the International Science Council.
+Reference `UnitSystem` based on Committee on Data of the International Science Council.
 
 ```Julia
 julia> josephson(CODATA) # Hz⋅V⁻¹
@@ -387,9 +387,12 @@ $(luminousefficacy(International))
 @doc """
     Meridian = EntropySystem(Metric,𝟏,em,em^3,𝟏,τ/𝟐^6/𝟓^7,milli)
 
-Systeme International d'Unites (the SI units) adopted as the preferred `UnitSystem`.
+Modern ideal `Meridian` system defined by France's original `earthmeter` definition.
 
 ```Julia
+julia> greatcircle(Meridian) # em
+$(greatcircle(Meridian))
+
 julia> boltzmann(Meridian) # eJ⋅K⁻¹
 $(boltzmann(Meridian))
 
@@ -416,9 +419,12 @@ $(luminousefficacy(Meridian))
 @doc """
     MeridianEngineering = EntropySystem(MetricEngineering,𝟏,em,em^3,𝟏,τ/𝟐^6/𝟓^7/g₀^2,milli)
 
-Systeme International d'Unites (the SI units) based on kilogram and kilopond units.
+Modern ideal engineering `UnitSystem` variant of the original French `Meridian` system.
 
 ```Julia
+julia> greatcircle(MeridianEngineering) # em
+$(greatcircle(MeridianEngineering))
+
 julia> boltzmann(MeridianEngineering) # kegf⋅em⋅K⁻¹
 $(boltzmann(MeridianEngineering))
 
@@ -633,7 +639,7 @@ $(rationalization(Kennelly))
 @doc """
     GravitationalMetric = EntropySystem(Metric,𝟏,𝟏,g₀)
 
-Systeme International d'Unites (the SI units) based on hyl and kilopond units.
+Standard `GravitationalMetric` system based on `hyl` and `kilopond` units.
 
 ```Julia
 julia> boltzmann(GravitationalMetric) # kgf⋅m⋅K⁻¹
@@ -662,7 +668,7 @@ $(luminousefficacy(GravitationalMetric))
 @doc """
     GraviationalSI2019 = EntropySystem(SI2019,𝟏,𝟏,g₀)
 
-Systeme International d'Unites (the SI units) based on hyl and kilopond units.
+Gravitational Systeme International d'Unites based on `hyl` and `kilopond` units.
 
 ```Julia
 julia> boltzmann(GravitationalSI2019) # kgf⋅m⋅K⁻¹
@@ -691,9 +697,12 @@ $(luminousefficacy(GravitationalMetric))
 @doc """
     GravitationalMeridian = EntropySystem(Metric,𝟏,em,g₀*em^3,𝟏,τ/𝟐^6/𝟓^7/g₀,milli)
 
-Systeme International d'Unites (the SI units) based on hyl and kilopond units.
+Gravitational `UnitSystem` variant of the original French `Meridian` unit defintion.
 
 ```Julia
+julia> greatcircle(GravitationalMeridian) # em
+$(greatcircle(GravitationalMeridian))
+
 julia> boltzmann(GravitationalMeridian) # kegf⋅em⋅K⁻¹
 $(boltzmann(GravitationalMeridian))
 
@@ -778,7 +787,7 @@ $(luminousefficacy(KKH))
 @doc """
     IAU☉ = EntropySystem(Metric,DAY,au,GM☉/G)
 
-Astronomical (solar) `UnitSystem` defined by International Astronomical Union.
+Solar `UnitSystem` defined by International Astronomical Union and `solarmass`.
 
 ```Julia
 julia> boltzmann(IAU) # M⊙⋅au²⋅D⁻²⋅K⁻¹
@@ -802,27 +811,27 @@ $(molarmass(IAU))
 julia> luminousefficacy(IAU) # lm⋅D³⋅M☉⁻¹⋅au⁻²
 $(luminousefficacy(IAU))
 
-julia> gaussgravitation(IAU) # au³ᐟ²⋅M☉⁻¹ᐟ²⋅D⁻¹
+julia> gaussgravitation(IAU) # D⁻¹
 $(gaussgravitation(IAU))
 ```
 """ IAU☉, IAU
 
 @doc """
-    IAUE = EntropySystem(Metric,DAY,au,GME/G)
+    IAUE = EntropySystem(Metric,DAY,LD,GME/G)
 
-Astronomical (Earth) `UnitSystem` defined by International Astronomical Union.
+Astronomical (Earth) `UnitSystem` defined by `lunardistance` around the `earthmass`.
 
 ```Julia
-julia> boltzmann(IAUE) # ME⋅au²⋅D⁻²⋅K⁻¹
+julia> boltzmann(IAUE) # ME⋅LD²⋅D⁻²⋅K⁻¹
 $(boltzmann(IAUE))
 
-julia> planckreduced(IAUE) # ME⋅au²⋅D⁻¹⋅rad⁻¹
+julia> planckreduced(IAUE) # ME⋅LD²⋅D⁻¹⋅rad⁻¹
 $(planckreduced(IAUE))
 
-julia> lightspeed(IAUE) # au⋅D⁻¹
+julia> lightspeed(IAUE) # LD⋅D⁻¹
 $(lightspeed(IAUE))
 
-julia> vacuumpermeability(IAUE) # ME⋅au²⋅C⁻²
+julia> vacuumpermeability(IAUE) # ME⋅LD²⋅C⁻²
 $(vacuumpermeability(IAUE))
 
 julia> electronmass(IAUE) # ME
@@ -831,27 +840,30 @@ $(electronmass(IAUE))
 julia> molarmass(IAUE) # ME⋅mol⁻¹
 $(molarmass(IAUE))
 
-julia> luminousefficacy(IAUE) # lm⋅D³⋅ME⁻¹⋅au⁻²
+julia> luminousefficacy(IAUE) # lm⋅D³⋅ME⁻¹⋅LD⁻²
 $(luminousefficacy(IAUE))
+
+julia> turn(IAU)/gaussianmonth(IAU) # D⁻¹
+$(turn(IAU)/gaussianmonth(IAU))
 ```
 """ IAUE
 
 @doc """
-    IAUJ = EntropySystem(Metric,DAY,au,GMJ/G)
+    IAUJ = EntropySystem(Metric,DAY,JD,GMJ/G)
 
-Astronomical (Jupiter) `UnitSystem` defined by International Astronomical Union.
+Astronomical (Jupiter) `UnitSystem` defined by `jupiterdistance` around the `solarmass`.
 
 ```Julia
-julia> boltzmann(IAUJ) # MJ⋅au²⋅D⁻²⋅K⁻¹
+julia> boltzmann(IAUJ) # MJ⋅JD²⋅D⁻²⋅K⁻¹
 $(boltzmann(IAUJ))
 
-julia> planckreduced(IAUJ) # MJ⋅au²⋅D⁻¹⋅rad⁻¹
+julia> planckreduced(IAUJ) # MJ⋅JD²⋅D⁻¹⋅rad⁻¹
 $(planckreduced(IAUJ))
 
-julia> lightspeed(IAUJ) # au⋅D⁻¹
+julia> lightspeed(IAUJ) # JD⋅D⁻¹
 $(lightspeed(IAUJ))
 
-julia> vacuumpermeability(IAUJ) # MJ⋅au²⋅C⁻²
+julia> vacuumpermeability(IAUJ) # MJ⋅JD²⋅C⁻²
 $(vacuumpermeability(IAUJ))
 
 julia> electronmass(IAUJ) # MJ
@@ -860,8 +872,11 @@ $(electronmass(IAUJ))
 julia> molarmass(IAUJ) # MJ⋅mol⁻¹
 $(molarmass(IAUJ))
 
-julia> luminousefficacy(IAUJ) # lm⋅D³⋅MJ⁻¹⋅au⁻²
+julia> luminousefficacy(IAUJ) # lm⋅D³⋅MJ⁻¹⋅JD⁻²
 $(luminousefficacy(IAUJ))
+
+julia> sqrt(gravitation(IAUJ)*solarmass(IAUJ)/jupiterdistance(IAUJ)^3) # D⁻¹
+$(sqrt(gravitation(IAUJ)*solarmass(IAUJ)/jupiterdistance(IAUJ)^3))
 ```
 """ IAUJ
 
@@ -1179,7 +1194,7 @@ $(luminousefficacy(FFF))
 @doc """
     MPH = EntropySystem(FPS,HOUR,mi,𝟏)
 
-Miles, pound, hour specification based on `FPS` absolute `UnitSystem`.
+Mile-pound-hour specification based on `FPS` absolute `UnitSystem`.
 
 ```Julia
 julia> boltzmann(MPH) # lbf⋅mi²⋅hr⁻²⋅F⁻¹
@@ -1211,6 +1226,9 @@ $(luminousefficacy(MPH))
 Nautical miles, kilo-earthgram, hour specification based on `Meridian` definition.
 
 ```Julia
+julia> greatcircle(Nautical) # nm
+$(greatcircle(Nautical))
+
 julia> boltzmann(Nautical) # keg⋅nm²⋅hr⁻²⋅K⁻¹
 $(boltzmann(Nautical))