What's a "Fence?"

[Contenderizer]

I have heard the term "fence" used when describing (older) shotguns, but I am confused as to its meaning. Can anyone help?

[Brithunter]

Ahhh I believe that the fence is the raised area behind the barrels on the action often engraved.

[ben-t]

The standing breech through which the firing pins protrude and as stated above.

[Contenderizer]

Thanks both of you ... and by the way, you are both correct. Here is another definition of that I have found since posting my question:

Hemispherical outgrowths of the receiver of a double gun that mate with the breech ends of the barrels. The term derives from the flanges (or fences) in this position on a muzzle loading gun that were designed to protect the eyes of the shooter from sparks and escaping gasses.