If you try to express "monday before second thursday in month" (announce for our monthly UUG meeting) you might want to setup a cron like 0 0 5-11 * 1 ~/bin/announce.sh Following the "Note" (see patch) section about the two day-fields this would end in "every day from 5th to 11th plus every monday". Therefore you cannot express "monday before second thursday in month". If the behaviour of the two fields would be logical "and" it should work and if you really need to express "every day from 5th to 11th plus every monday" you easily could set up two lines with an asterisk for the 3rd or the 5th field. So we have some unneded redundancy here plus the lack of a reasonable facility. So this "feature" should go into the "Bugs" section of crontab.5 Maybe someone would patch the behaviour.
(In reply to rabe from comment #0) Hi from the future, The behavior here is actually intended, and it would be rather jarring to many if this were to change. This is also how it works on pretty much every *nix-like server I've worked on, so suddenly documenting it as a bug when its behavior is quite deliberate and consistent with other cron implementations would also be rather jarring. Ultimately, I think this is a "works as intended" all around.