One of my early day student projects from 1999, maintained by Ivan Popov from 2002 until recently I picked it up again from http://www.kernel.org/pub/linux/libs/pam/modules.html.
CODA is an advanced Network Filesystem.
I used it a lot to replicate and backup my /home folder (more recently rsync has replaced the functionality for me).
PAM is a gnu/Linux standard for handling login and authentication tokens.
pam_coda transparently creates coda-access-token(s) when a user logs in. It unobtrusively handles coda sessions allowing to integrate CODA and kerberos into everyday GNU/Linux use: