A．external to the music, imposed in most cases by the interpretational criteria of critics and listeners
B．interesting but unnecessary for the enjoyment of these pieces of music by most listeners
C．evidence that socially-grounded codes are composed into music, and not simply the product of interpretation
D．a means by which familiar and well-loved music can be invested with new and arguably more positive values
E．evidence for a fundamental difference between the music of the avant-garde and more traditional varieties