Thankyou nataraj and keith - I'll follow your suggestions and see how I go. I've got this far using my own logic processes, so it came as a bit of a surprise to find that what I was doing was the sa ...
I'm having a lot of trouble with this Intersection of 4 Groups concept. In the example given by Someone, don't the restrictions "In column 1 exact twice" and "In column 3 exact twice& ...