Assertion: progressive rock | /r/CapableOf | know as art rock
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: Bruce Eder's essay The Early History of Art-Rock/Prog Rock states that "'progressive rock,' also sometimes known as 'art rock,' or 'classical rock'" is music in which the "bands [are] playing suites, not songs; borrowing riffs from Bach, Beethoven, and Wagner instead of Chuck Berry and Bo Diddley; and using language closer to William Blake or T. S. Eliot than to Carl Perkins or Willie Dixon.