Rene Grothmann, mathematic's teacher at the catholic university of Eichstätt (Germany), made for his software powerful and reliable algorithms to manage geometrical objects and relations between them : this makes it possible to make very complex geometrical constructions.
For the graphical interface, Rene also did a very great work concerning the interaction between geometric objects and user, what also makes it possible to use C.a.R. with young pupils in primary schools.
CaRMetal is based on C.a.R. : it includes all of its functionalities - or almost - but follows a different approach from the graphical interface point of view. It's not just a different design - which would not make sense - but instead it gives another way to reach functionnalities.
This new interface, programed by Eric Hakenholz (mathematic's teacher), delivers direct access and instant effects to numerous actions instead of intermediate steps, like modal dialog boxes. Constructions in CaRMetal are made with a main palette and two inspectors : the first one is in charge of macros' management and the other one concerns objects properties.
CaRMetal is an open source freeware distributed under GNU general public licence (GPL). It's based on C.a.R. sources and can be used on Mac OS X, Windows and Linux. For the moment, CaRMetal is available in many languages.