it is on other rcs.
Below, you can see rc.M that starts httpd on system init (it is written on the head of rc.M).
When you unlock the rights on rc.httpd, it enables rc.M that runs on system startup to run it. Other rcs stops it when a halt, or a reboot is called.
You can see it with a grep. I did it on a Slackware (great choice).
$ grep http rc.*
rc.0:if [ -x /etc/rc.d/rc.httpd ]; then
rc.0: /etc/rc.d/rc.httpd stop
rc.6:if [ -x /etc/rc.d/rc.httpd ]; then
rc.6: /etc/rc.d/rc.httpd stop
rc.K:if [ -x /etc/rc.d/rc.httpd ]; then
rc.K: /etc/rc.d/rc.httpd stop
rc.M:if [ -x /etc/rc.d/rc.httpd ]; then
rc.M: . /etc/rc.d/rc.httpd start