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

Version 4.0.0 is not backward compatible to previous versions. A tested conversion script is provided to transform models and libraries of previous versions 3.x.y to the new version. Short Overview:

• About 649 issues (including 432 pull requests) have been addressed for this release.
• This version is based on the recent Modelica language standard version 3.4.
• The library version (i.e., "4.0.0") follows semantic versioning using the convention MAJOR.MINOR.BUGFIX (see Version Management for details) and was decoupled from the version of the utilized version of the Modelica language standard.
• Obsolete classes of previous versions 3.x.y have been replaced.
• Obsolete classes, that could not be automatically converted to alternative implementations, have been moved to library ObsoleteModelica4.
• Major emphasis was put on improvements of the overall quality with respect to class naming and package structuring, conventions and style guide-lines, icons, documentation style and example models. The following sublibraries have been renamed.
  1. Modelica.SIunits → Modelica.Units.{SI, NonSI, Conversions}
  2. Modelica.Electrical.MultiPhase → Modelica.Electrical.Polyphase
  3. Modelica.Electrical.QuasiStationary → Modelica.Electrical.QuasiStatic
• The licenses of the utilized open-source third-party software components as well as the BSD 3-clause license of the Modelica Standard Library itself are available as separate resources.

The exact difference between package Modelica version 4.0.0 and version 3.2.3 is summarized in a comparison table.

The following Modelica packages have been tested that they work together with this release of package Modelica (alphabetical list). Hereby simulation results of the listed packages have been produced with package Modelica version 3.2.3 and compared with the simulation results produced with version 4.0.0 Beta.1. The tests have been performed with Dymola 2020/2020x/2021:

The following new libraries have been added:

The following new components have been added to existing libraries:

The following existing components have been improved in a backward compatible way:

The following existing components have been changed in a non-backward compatible way:

The following critical errors have been fixed (i.e., errors that can lead to wrong simulation results):