Invalidity of Endowment in Cases of Selling License

In discussion of selling endowment, the general principle is lack of selling endowment. There is disagreement between jurists in getting out of this general rule, but most jurists and even lawyers and civil law of Iran believe in selling endowment in certain cases. In case of selling endowment in answering to this basic question that if endowment is being invalid in selling or endowment remains in endowment case until the time of selling endowment and is been invalid by external selling. There are three theories: the first theory believes in being invalid of endowment by selling. The second theory believes in being invalid of endowment by external selling and third theory by expressing 8 cases as the cases of selling licenses believe in extending and in some cases believe in being invalid of endowment by selling and in some cases believe in being invalid by external selling.