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This information is part of the Modelica Standard Library maintained by the Modelica Association.

The following conventions are used in package SIunits:

  • Modelica quantity names are defined according to the recommendations of ISO 31. Some of these name are rather long, such as "ThermodynamicTemperature". Shorter alias names are defined, e.g., "type Temp_K = ThermodynamicTemperature;".
  • Modelica units are defined according to the SI base units without multiples (only exception "kg").
  • For some quantities, more convenient units for an engineer are defined as "displayUnit", i.e., the default unit for display purposes (e.g., displayUnit="deg" for quantity="Angle").
  • The type name is identical to the quantity name, following the convention of type names.
  • All quantity and unit attributes are defined as final in order that they cannot be redefined to another value.
  • Similar quantities, such as "Length, Breadth, Height, Thickness, Radius" are defined as the same quantity (here: "Length").
  • The ordering of the type declarations in this package follows ISO 31:
      Chapter  1: Space and Time
      Chapter  2: Periodic and Related Phenomena
      Chapter  3: Mechanics
      Chapter  4: Heat
      Chapter  5: Electricity and Magnetism
      Chapter  6: Light and Related Electro-Magnetic Radiations
      Chapter  7: Acoustics
      Chapter  8: Physical Chemistry
      Chapter  9: Atomic and Nuclear Physics
      Chapter 10: Nuclear Reactions and Ionizing Radiations
      Chapter 11: (not defined in ISO 31-1992)
      Chapter 12: Characteristic Numbers
      Chapter 13: Solid State Physics
  • Conversion functions between SI and non-SI units are available in subpackage Conversions.