All software and documentation that is part of the TUTOS software distribution is governed by the General Public License (GPL) originaly conceived by the Free Software Foundation ('Free as in speech, not as in beer'). Below is the official text of this license. Don't worry too much about it. Basically you are allowed change, study, sell and install the software as much as you like. The only thing you are not allowed to do is prevent others to exercise this freedom too. But as mentioned before, the official legal terms are as mentioned in the next section.