This package provides an alternative mechanism to boot the system, to shut it down and to change runlevels. The /etc/rc?.d/* links will be converted into one single configuration file /etc/runlevel.conf instead, which is easier to administrate than symlinks, and is also more flexible.
The package will automatically convert your existing symlinks into the file method on installation, and convert the file back into symlinks on removal. Both mechanisms are compatible through /etc/init.d/rc, /etc/init.d/rcS, /usr/sbin/update-rc.d, and /usr/sbin/invoke-rc.d scripts.