    def compileIfSignalHead(self, line):
        # If signal head <head name> does [not] show <appearance> [or ...]
        if logLevel > 2: print '  {} - {}'.format(self.threadName, line)
        pattern = re.compile('\s*If\s+signal\s+head\s+(.+\S)\s+does\s+(not\s)?show\s+(.+\S)')
        result = re.findall(pattern, line)