 The distinction between a derivation tree and a constituent tree is made in several theories of grammar. In Tree Adjoining Grammars (TAGs) the different scope readings of the sentence about loving a woman differ in the order in which the noun-phrases are substituted in the basic tree. A classical example in Chomskyan grammar is The shooting of the hunters was bloody, which is ambiguous between the hunters shooting, or the hunters being shot at. The two readings come from two different sources: one in which the hunters is the subject of the sentence, and one in which it is the object.