What is a word that describes the class that "background" and "foreground" are members of?

I think of foreground and background as planes.

They are relative locations, as opposed to absolute locations. You cannot buy a plane ticket to foreground, but sitting at my desk, the copy holder and my pencil are in the foreground relative to the file cabinet and the wall. The cabinet and wall are in the background relative to the other two items.

If I turn and look out the window, the leaves on the tree are in the foreground relative to the building in the background.

Foreground and background are everywhere- they are relative to each other and relative to the space.

would configuration fit the bill?