In case you were wondering, Carl Henze is not Hans Werner Henze, the contemporary composer (died 2012), whom we know from Leonora Spangenberger's excellent performance of his Drei Tentos. Carl Henze is an older composer (died 1946), whose works passed into the public domain this year. Why am I telling you all of this? Because I was wondering how Henze's works got to the public domain.
Yisrael van Handel
Modi'in Ilit, Israel