Copyright (c) 2001 Massimo Zaniboni.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections , with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
This document is a work in progress. I do not know very well English so feel free to fix errors. I think that for you is better a bad English documentation than a good Italian one.