I was stumped but I will be trying this. Passage from top of pg 66. from strategy and tactics pdf manual that is for the ACHTUNG: Panzer games and Blaze of Armor
you can download (link below).
"To set firing line, do the following: select a commander/spotter and press [G]. Then set firing line (right click); draw a
line to make it longer.) Number inside the line shows fire accuracy: 0 for minimum, 100 for maximum. Accuracy depends on
how far the spotter is and on the firing line visibility. Accuracy will increase if the spotter sees the firing line and is not under
fire himself. Press [`] to check the firing line visibility."http://www.graviteam.com/Manuals/tactics_manual_eng.pdf