Dear Duncan and Oleg, thanks for your answers. For the moment, I'll use functions. Happy new year, Claudia
Claudia Beleites Dipartimento dei Materiali e delle Risorse Naturali Universit? degli Studi di Trieste Via Alfonso Valerio 6/a I-34127 Trieste phone: +39 (0 40) 5 58-34 47 email: cbeleites at units.it