Minecraft wiki entry for Item_Frame, associated text: Players can place items in the frame by using the item. If a map is placed in an item frame, it enlarges to show the map in the size of a full block, with the item frame's location displayed as a green pointer on the map, pointing in the direction the item frame is facing. If this is done in the Nether, the green cursor spins around similar to the white cursor (players). If an item in an item frame has been renamed using an anvil, it displays its custom name when the cursor is over the item frame. If the player places a block inside the frame, it is displayed in miniature half in, half out of the block. This can be most notably seen on stairs or slabs.