Page 7.1.

Firstly, we are going to draw in our XY line. You should recall that the XY line is the line representing the fold line between the V.P. and the H.P. and the line of intersection between the E.V.P and the H.P.. So here is a lined out sheet with the XY drawn in heavy across the sheet. Black lines are heavy, and green lines are light because they are only construction lines.