cron behavior

[jbk]

I want my full backup script to run every fourth Monday and
I thought the following sintax would do that, but this
morning it ran again, this is the second Monday in the
cycle.

'15 4 * * 1/4 /etc/backup/backup monday
>>/var/log/backup/tape.log'

Does this syntax only work on the HOUR & DAYS_OF_MONTH
fields? The man page doesn't say.

The backup script is dependent on the DAY_OF_WEEK field, I
could change this but it would be two weeks of testing
again.

Jim Kelly-Rand