+<indexterm><primary>Constitution, U.S.</primary><secondary>on creative property</secondary></indexterm>
+<indexterm id='idxconstitutionuscopyrightpurposeestablishedin' class='startofrange'><primary>Constitution, U.S.</primary><secondary>copyright purpose established in</secondary></indexterm>
+<indexterm id='idxconstitutionusprogressclauseof' class='startofrange'><primary>Constitution, U.S.</primary><secondary>Progress Clause of</secondary></indexterm>
+<indexterm><primary>copyright</primary><secondary>constitutional purpose of</secondary></indexterm>
+<indexterm><primary>copyright</primary><secondary>duration of</secondary></indexterm>
+<indexterm id='idxcreativepropertyconstitutionaltraditionon2' class='startofrange'><primary>creative property</primary><secondary>constitutional tradition on</secondary></indexterm>
+<indexterm id='idxprogressclause' class='startofrange'><primary>Progress Clause</primary></indexterm>
+<indexterm><primary>copyright</primary><secondary>duration of</secondary></indexterm>