I've had the Oly for over a year, but have never really looked at the preset filters.
When I came home this afternoon I was sitting in the car while I listened to the end of a news item and had a look at the Key Line Filter.

Very interesting.
This is the back of my house, looking like something out of a children's picture book.
Bear with me, til I've worked through this:)

Have just returned from a lovely meal with Bob and Adele.