Took a moment for me to realize what I was looking at, but I'm sure I saw something like this in a (U.S.) home security book years ago.

Is that a separate keyhole to the left of the lower "receptacle" U-ground? I wonder why they couldn't use one of the other slots to avoid the extra hole.

Oh, and aren't those "receptacles" upside down? Or is that so you pick out the safe from all the real ones? [Linked Image]

Runs & ducks for cover......