Provides support for Dimensional Analysis.

The difference between dimensional models lies in the assumptions each makes and, in consequence,the operations each permits. For example, the summation of a length and a time is not allowed by the standard model, but is quite valid in a relativistic context.

The names and characteristics of the models are presented in the following table:

Model	Class	Defining Characteristics	DefaultQuantityFactory Output CommonUnits
Standard	"StandardModel"	per Système Internationale	Length: m;  Mass: kg;  Duration: s;  ElectricCurrent: A;  Temperature: K;  AmountOfSubstance: mol;  LuminousIntensity: cd
Relativistic	"RelativisticModel"	1 = c	Length, Duration: s;  Mass: eV;  ElectricCurrent: A;  Temperature: K;  AmountOfSubstance: mol;  LuminousIntensity: cd
High-Energy	"HighEnergyModel"	1 = c    = k    = ePlus	Length, Duration: ns;  Mass, Temperature: GeV;  ElectricCurrent: 1/ns;  AmountOfSubstance: mol;  LuminousIntensity: cd
Quantum	"QuantumModel"	1 = c    = k    = µ0    = hBar	Length, Duration: 1/GeV;  Mass, Temperature, ElectricCurrent: GeV;  AmountOfSubstance: mol;  LuminousIntensity: cd
Natural	"NaturalModel"	1 = c    = k    = µ0    = hBar    = G	Length, Mass, Duration, ElectricCurrent, Temperature: 1;  AmountOfSubstance: mol;  LuminousIntensity: cd

This class represents the standard model.