Multics Emacs Text Editor User's Guide - CH27-00F
Multics Emacs Extension Writer's Guide - CJ52-01
The emacs keystroke to insert the declaration of an entrypoint exists in pl1-mode as ESC-^D. Underlying it is the get_entry_point_dcl_ subroutine, which gets the declaration information from two independent sources: from the entry descriptors created before each entrypoint by the PL/I compiler; or from a data segment found by the "declare" search paths containing declarations for ALM entrypoints, including gate entrypoints, etc.
The display_entry_point_dcl (depd) command displays findings from get_entry_point_dcl_ as its command output. The emacs keystroke invokes get_entry_point_dcl_$emacs, which returns the output directly to Emacs in a format acceptable to LISP routines.