I can't understand what you mean ....
rc4.d is just a folder where inside are links for processes that are inside /etc/init.d/, rc4 is what we call Runlevel 4, this means that if your box enters in runlevel 4 all processes inside this folder begining with S will be start (in the numeric order) and all starting with a K will be killed (closed in numeric order too), its like when you reboot your box, it goes to runlevel 6 and execute all processes inside /etc/rc6.d. Debian usually uses runlevel 2 to 5 for GUI and most(to not say ALL) UNIX distribution uses runlevel 1 or S to single mode.
take a look:
http://en.wikipedia.org/wiki/Runlevel
[ ]'s
INIT 4(rc4.d)
