(S (S (PP (IN Besides) (BASENP (NN attribution))) (COMMA ,) (S (BASENP (DT the) (NN license)) (VP (VBZ requires) (SBAR (IN that) (S (BASENP (NNS modifications)) (VP (VBP are) (VP (VP (VP (VBN made) (S (ADJP (JJ available)))) (PP (IN under) (NP (BASENP (DT the) (JJ same) (NNS conditions)) (COMMA ,) (NP (BASENP (DT a) (NN principle)) (VP (VBN known) (PP (IN as) (QT (DQL ``) (BASENP (NN copyleft)) (DQR '')))))))) (CC and) (VP (ADVP (RBS most) (RB frequently)) (VP (VBN applied) (PP (TO to) (NP (BASENP (NN computer) (NN software)) (PP (JJ such) (PP (IN as) (BASENP (DT the) (JJ free) (NN operating) (NN system) (NNP Linux))))))))))))))) (PERIOD .))