Confused about connection between an option in rc.conf and the associated action?

[Ola Theander]

Dear subscribers

I'm slightly confused about enabling an option in rc.conf and the associated
action? E.g. say that I enable gateway_enable="YES" or maybe
dhcpd_enable="YES", how does FreeBSD associate this simple line to the
associated action? I've had a theory that adding e.g. test_enable="YES" to
rc.conf would trigger the execution of the file /etc/rc.d/test.sh at boot
time but it seems like this isn't how it's done.

Any clarification on this matter would be greatly appreciated.

Kind regards, Ola Theander