Hi Mark,
That is interesting as I did not have the Penola R7-11 so I did some checking in Bet Selector and found the spell sign appears next to a runner from 84 days and more, or a 12 week period. So I have re set this in the Mark lay system.
I previously had it set to 90 days or 3 months

In the Australian newspaper the key to symbols says the spell sign indicates a spell of three months or more.