Keep in mind that the FAQ changes this rule, it makes a lot less sense if you follow the version in the rulebook.
The rule book version, read strictly, disallows ranged attacks in walls at the edge if your zone! FAQ sorts it
Actually the rule book says this under the heading Attacking Walls:
"A creature in either of the zones next to a wall may make a melee attack against that wall. Ranged attacks may target a wall if either of the adjacent zones is in range and LoS. Walls do not occupy a zone, and are not affected by zone attacks or spells that target a zone."
It's not quite as clearly stated, but it would still be interpreted that same way as the FAQ.
Doesn't seem to be that way to me. Consider the following situation:
+---+---+
| A ║ B |
+===+---+
| X | |
+---+---+
There is a creature at X, with a ranged attack that has range 1-2. There's walls between the archer at X and zone A, and between zone A and zone B.
- X has LOS to B, B is in range and adjacent to the wall between A and B; so per the rulebook, it would be able to target the wall between A and B.
- X has no LOS to A, and the zone of X itself is not in range, so neither of the zones that are adjacent to the wall between A and X are both in LOS and range.
Thus per the rulebook, the archer would not be able to shoot the wall between A and X, but it would be able to shoot the wall between A and B.
The FAQ fixes this. It says:
In order for a creature to be able to perform a ranged attack against a wall, it must (1) have LoS to the wall (trace LoS to the center of the border where the wall resides), and (2) be in range of at least one of the zones the wall borders.
The archer at X has LOS to the wall between A and X, but not to the wall between A and B. A is in range, so it can attack the wall between A and X (and that A and B are in range doesn't matter for the wall between A and B).