listfile

reads a set of C-source files and generates a two-column listing of those sources

These are the source listings and cross reference table of the CDG program that generated these listings and cross reference table...
In other words: the program that is built from these sources generates documentation that looks like this.
Peter Knoppers - [e-mail] - You can find a link to the latest version of CDG in http://cardit.et.tudelft.nl/~knop
Makefile
cdg.h
main.c
page.c
y.tab.h
parse.c
scan.h
scan.l