May be I did not explain it well. The timber is laying East and West with the referance face up and the referance side facing South. I hang the framing sq on the referance face with the blade hanging down on the south side. I mark off 2 inches from the cornerS off the bladeS over to the north on the referance face and again 6 inches from the corners of the sq. I do this on both the referance face and the bottom side On the bottom side I measure over from the edge of the blade I never move the sq while I do this. Then I go to other end and repeat the process There are marks 2 inches and 6 inches over from the referance edge on the refeance face and 2 and 6 on the bottom from a imajinary point out in space if you want to call it. but it would be perpendicular to the refeance corner. I then snap a line from these points. I then have one side of the tenon and one side of a mortise pocket if I am right so far I can conect the tenon points at the end of the timber and the tenon should be perpendicular to the referance face.
