'Blind Spots for Rear Guns' clarification

By Vulcan Jedi, in Wings of War (WWI)

Does this rule mean that you can't fire at a target that is too close (the first half of the ruler touching any point of the target card), or does it mean that you can't shoot if the ruler crosses the tail of your plane, which makes more sense.

Thanks,

VJ

Using the optional aircraft art rules for representing the planes versus the shape of the card - now rear-firing guns have a blindspot (you cannot shoot) where the ruler crosses the tail of your plane AND the target is in the first half of the ruler.