http://privateerpressforums.com/showthr ... ost3724072
tl;dr
DarkLegacy wrote: All attacks go from nearest edge to nearest edge of models for determining range. Pg. 40 of Prime Rules Digest.
If you extended the examples made in this thread out to be a ranged or magic attack, everyone would agree that the model can be targeted and attacked. In this edition, it was intended and was simplified to make all attacks the same. All ranges extend out completely around a model, be it for a melee, ranged, or magic attack. You must be able to draw line of sight (LOS) to be able to make the attack.
This does mean that the examples in the book are misleading because they imply front arc only for melee ranges. I am not sure if this will be fixed.
This also means that things have changed a bit for Acrobatics and charging over a model. As long as a model with Acrobatics doesn't charge directly over a same size or smaller base, it can now go completely past said model and turn to face at the end. You cannot have the charge target completely subsumed under the charging models base as it leaves melee range at that point. If any portion of the charge target's base remains in melee range, it is acceptable.
Front arc does not extend 360 degrees. It is still the front 180 degrees of the model, per page 21 of Prime Rules Digest under Facing.