The rules given so far allow front rank models to shoot, but we also want to allow models in the second rank to shoot (they take aim over crouched or stooping fellows in the front rank). Therefore, models in the second rank can use the line of sight and forward arc of the model directly in front of them for the purposes of all shooting attacks (including stand and shoot reactions). In simple terms, this allows units to fire in two ranks.

Models further back than the second rank of a unit are assumed to have their line of sight blocked by models further forward, and so will not normally be able to shoot.