Note:  These stamps were cut from a sheet of 200 stamps into individual sheets (panes) of 50 stamps.  The guide line arrows were placed at the edge of the sheets, midway between the sheets to help the person who was cutting the sheets.  (see picture) Therefore to cut this sheet of 200 stamps into 4 sheets of 50 stamps, there would have been only 4 ARROWS.  This ARROW is uncommon and would only occur in 1/50 stamps (one per sheet), but because of the position of the arrows (top center, bottom center, left center, right center), each arrow is unique and would only occur 1/200 stamps.