European Space Agency has designed a prototype for component-based software framework for a satellite Attitude and Orbit Control System (AOCS). Their home page is at => http://www.softwareresearch.net/AocsFrameworkProject/ProjectHomePage.html It has been programmed in C++ in preference to Ada 95 - read inter alia http://www.softwareresearch.net/AocsFrameworkProject/DesignPrinciples.html paragraph "Language Compatibility" for the reasons behind the decission. The main reason is lack of multiple inheritance in Ada 95. regards /søren