${INIT_SYSTEM} is used to select the type of init system in use on
the system, and currently can be either "rc.d" for the NetBSD rc.d
system, or "smf" for the Solaris Service Management Facility
system.
pkgsrc/mk/init/smf.mk is pkgsrc/mk/smf.mk with some very minor
modifications to fit into the "init" framework.
