Which daemon or Linux command makes init 0 or shutdown happen when I press the power button?

When I press the power button, Linux goes to init 0 (or shutdown clean). In the old times (2003) I had to configure acpid to give the shutdown function to the power button. Today on Slackware-current I did: cat /etc/apci/event/default #event=button power.* #action=/sbin/init 0 and I see the function is commented with # which mean disabled. So the question is: which daemon provides the init 0 function when I press the power button? Other distributrion mnay have systemd, but on Slackware we don't have systemd. Is it acpid even though the power button lines are commented?