Thanks to Roberto A. Foglietta for xdm:
Title: xdm.tczl
Description: xdm
Version: 1.1.18
Author: Various
Original-site: https://launchpad.net/ubuntu/+source/xdm
Copying-policy: GNU GPL
Size: 104k
Extension_by: Roberto A. Foglietta
Comments: In the X Window System, an X display manager runs
as a program, that allows the starting of a session
on an X server from the same or another computer.
A display manager presents the user with a login
screen which prompts for a username and password.
A session starts when the user successfully enters
a valid combination of username and password.
tc@box:~/tmp/tce$ tail -n1 /opt/bootlocal.sh
grep -q xdm /proc/cmdline && sudo xdm
tc@box:~/tmp/tce$ head -n1 ~/.xsession
test -r ./profile &&. ./profile
Change-log: 2009/06/07 Description changed
2009/06/05 First version
Current: 2009/06/07 Description changed