On the Minelab Etrac

I know the lower right hand corner of the quick mask is iron, but what is the upper left hand corner made up of? co 1-25??

Foil, small gold, lead, nickels

Going by memory, the upper left corner of the graph are low numbers for iron and conductivity. In other words 1 ferrous and 1 condt are the first coordinate points in the upper left corner. From top to bottom horz, reads ferrous (1 to 30something) and left to right vertically,condt reads (1 to 50???). Upper right coordinates are low ferrous, high condt.
Lower right is high ferrous, low condt. Lower left is high ferrous, low condt. When you are in quick mask and want to disc iron, pushing the cursor button blacks out the highest numbers of ferrous starting at the bottom of the screen. As you push the cursor, the screen blackens from the bottom up (high ferrous).
I think the e-trac is easier to learn than the SE because of the 12 line and the way the coordinates are laid out on the screen all starting at 1-1 in the upper left corner, fits better in my head anyway. Hope my memory served you correctly markg.