Defending terrain?

[Theo]

I'm a bit confused about this. On p. 20 (of the 1.1 draft I'm using at the moment) it says:

DEFENDING THE EDGE OF A TERRAIN FEATURE (Fig. 25)
To defend the edge of a terrain feature, all of the defending element must be inside an area feature or beyond a linear feature or boundary; the feature?s defended edge must be in the element?s threat zone, and any frontal close combat opponent it has must be at least partially on the opposite side of the feature?s edge.

All well and good, but I can't find anything about the actual effects - if any - of defending the edge of a terrain feature. Is there any? I notice from p. 19 that, say, a boundary hedge or wall counts as difficult going (as does fixed obstacles), but is there any advantage to defending them other than your attacker being in DG and hopefully being a troop type that's penalized by this? Am I missing something?

[lorenzomele]

Elements defending a river edge are immune to pursuit.
Elements defending a terrain feature cannot be "corner contacted"

[Theo]

Elements defending a river edge are immune to pursuit.
Elements defending a terrain feature cannot be "corner contacted"

Thanks, I missed that.

But an element that can't be "corner contacted" can still be overlapped, right?

[lorenzomele]

Yes, "the corner contact" section in the rules I'm recalling is the group contacting with the front an enemy group in the corner and not having to line up.