A scene in Move3D is described by a Move3D Input File (MIF). A MIF contains the geometrical description of obstacles and of at least one mechanical system (robot)with its cinematics. A Move3D session always begins by the reading of a MIF, done by the function int p3d_read_desc(char *file) whose argument is a pointer on a MIF file. This function skims through the description file and executes the commands as soon as it reads them.