What does list in crontab do?

I'm maintaining a server which runs mailman. In it I find a crontab which looks like the following: 0 8 * * * list [ -x /usr/lib/mailman/cron/checkdbs ] && /usr/lib/mailman/cron/checkdbs 0 9 * * * list [ -x /usr/lib/mailman/cron/disabled ] && /usr/lib/mailman/cron/disabled ... When I type *list* I get > No command 'list' found .. My searches for "crontab list", "linux list command", "mailman cron list" bring up results for listing things. What does list in crontab do ? What command is list refering to ?