A model has a forward, flank and rear arc based on the direction that it is facing. We'll be using this later to work out what the model can attack, as well as calculating which side of the model an enemy will be able to charge as the game goes on.
A model's forward (or 'front'), flank and rear arcs extend out from its corners at 45° angles, forming four 90° quadrants. A unit's facings therefore are determined by the facing of its constituent models.