The Debian Free Software Guidelines ( DFSG ) is a set of guidelines ( rules ) that the Debian Project uses to decide whether a software license is a free software license , which is used to decide whether a piece of software can be included in Debian . The Debian Free Software Guidelines ( DFSG ) is a set of guidelines that the Debian Project uses to determine whether a software license is a free software license , which in turn is used to determine whether a piece of software can be included in Debian .