Dear OpenModelica interested, OpenModelica 1.5 Release Candidate 1! Here are the most important improvements of this OpenModelica 1.5 release candidate (see www.openmodelica.org). It is a release candidate available for testing, now available in both source and binary, compared to the previous 1.5 beta from Sept 19, which was only binary. Also, it is available on all three platforms Windows, Linux, and Mac. We are grateful for feedback and bug reports during the coming 2-3 weeks, before making the final release. This release has major improvements in the OpenModelica compiler frontend. Approximately 2.5 person-years of additional effort have been invested in the frontend compared to the 1.4.5 version, e.g., in order to have a more complete coverage of Modelica 3.0, mainly focusing on improved flattening in the compiler frontend. However, the coverage is not full Modelica 3.0 in this release, and the MultiBody and Media/Fluid libraries are not yet fully supported, which is the main goal for the current and immediate future development. The release includes major improvements of the flattening frontend part of the OpenModelica Compiler (OMC) including, but not restricted to: · Support for enumerations, both in the frontend and the backend. · Support for the inline annotation in functions. · Complete support for record constructors, also for records containing other records. · Full support for iterators, including nested ones. · Support for inferred iterator and for-loop ranges. · A new bidirectional external Java interface for calling external Java functions, or for calling Modelica functions from Java. · Support for Modelica 3.1 annotations. · Support for all MetaModelica language constructs inside OpenModelica. · OpenModelica now works also under 64-bit Linux. · Many bug fixes. The development work is being accelerated, supported by the expanding Open Source Modelica Consortium, currently 26 organizations - 15 companies/institutes and 11 universities. Thanks to all who contributed and worked hard for this release! Best regards, Peter Fritzson