pg. 08 from The Scenario Specific Rules for The Western Front, in Der Weltkrieg...
12-5 A sector is considered to be at least three hexes deep (a player may opt to make it deeper).
One of these hexes is the frontline.
The sector may bow inward as you move rearward from the front line (it may also bow outward if the Entente player wishes).
The Entente player may describe the edges of the sector as a hex adjacent to the front line, and then a hex adjacent to that, but not adjacent to the front line.
(Example: British sector has front line of 1006, 0907, and 0908. Second hex deep of sector would be hexes 0806 and 0807 [hex 0906 cannot be the second hex ‘deep’because it is also on the frontline]. Third hex deep of sector is hex 0707 only).
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