anacrontab中identifier的理解？

setamv

man anacron帮助中有下面这样的一句描述：

Anacron only considers jobs whose identifier, as specified in anacrontab(5), matches any of the job  command-line  arguments.   The job  command-line  arguments  can  be  represented by shell wildcard patterns (be sure to protect them from your shell with adequate quoting).  Specifying no job command-line arguments is equivalent to specifying "*"  (that is, all jobs are considered by Anacron).

请问上面提到的通配符是什么情况下用到呢？还有这句话主要讲的什么意思？英文不好，没看明白。谢谢了