I"m surprised they even have the option to use the old lat long crap. just a 10digit grid or 8 depending on the target size/type/location. you would hear the FAC or grunt on the ground telling you their location, type of enemy, enemy location, and direction of attack. personaly if their is air on dec we would just stop firing mortars. the air will be doing a splended job. if there is a real FAC on the ground you should hear "lightning!" be called out meaning .... he's an expert and knows what he's doing so you wont be nervouse about hitting friendly units.