Hi.

In Elisp manual -> Debugging -> Edebug -> Printing in Edebug, the manual
says

Other programs can also use custom printing; see cust-print.el fo rdetails.

http://git.savannah.gnu.org/cgit/emacs.git/tree/doc/lispref/edebug.texi#n875

, but cust-print.el is obsolete since emacs-24.3.

Thanks.