Can anyone explain me how the "Layers" function works? I don't unsderstand the meaning of the second parameter. Thank you -- Laurent CHAMPANEY - UVSQ Dept de Mecanique Centre de Mecanique des Milieux Continus RC 28 - Bat Descarte 78025 VERSAILLES Cedex Tel 01 39 25 30 26 - Fax 01 39 25 30 15