Fedora directory users - Jan 2008 - Documentation for libdna (auto uid/gid generation) ?

Does anyone know where I might find documentation for the libdna plugin? 
I''ve got fds 1.1 installed on my system and I''d like to test
out this feature but I''m not exactly sure how.  I''ve enabled
it in the plugin list (with no arguments).  Anyone set this up yet?