The "history" of the text of _the Cantos_ is labyrinthine for both
mechanical and political reasons.
 I think there
should be some words explaining the change
Indeed, the problem is that many of the changes to the text have been
quirky, even arbitrary.  The definitive study is by Barbara Eastman
_Ezra Pound's Cantos:  The Story of the Text 1948-1975_.  Orono, ME:
National Poetry Foundation, 1979.
Jon Ausubel