For the guns to be able to make sense of your adjustments, they must know the direction of the target from your position. You calculate this by taking a bearing with your compass on the target. Next you must say what the target is. You must be as precise as possible so that the guns can choose the correct ammunition, allocate priorities and decide on the amount of ammunition necessary to neutralise that particular target. The next piece of information that is required by the guns is what you want done about the target.
Smoke is used to frustrate enemy intentions.
This means that sufficient fire must be brought to bear to render the target ineffective in the current battle. Even tanks can be neutralised by artillery fire if their optics and radio antennae are damaged. Lastly the guns will need to know when you want them to fire and for how long. Hello G11, this is I33d, fire mission over. G11, Grid 834629, direction one, seven ,eight ,zero, magnetic, enemy platoon debussing from APCs, neutralise for three, minutes, report when ready wait out.