'/etc/insserv.conf* entries define system facilities.
Full format details are in man 8 insserv, but the basic structure is:
$variable          facility1 facility2
$second_variable   facility3 $variable
Any init script that specifies Required-Start: $second_variable needs to be
expanded to facility1 facility2 facility3.
Args:
data: A string of insserv definitions.'

def _ParseInsserv(self, data):

    parser = config_file.FieldParser()
    entries = parser.ParseEntries(data)
    raw = {e[0]: e[1:] for e in entries}
    facilities = {}
    for (k, v) in raw.iteritems():
        k = k.replace('<', '').replace('>', '')
        facilities[k] = v
    for (k, vals) in facilities.iteritems():
        self.insserv[k] = []
        for v in vals:
            self.insserv[k].extend(self._InsservExpander(facilities, v))
