When purchasing the White Plains S/S, always check to make sure you have full selvage (not trimmed) and that there are no perf separations.
-- The top 2 positions will have wide ~1" selvage at the outside press sheet edges.
-- The bottom 2 positions will have ~3/4" selvage at the outside press sheet edges.
-- All the inside edges will be ~1/2" selvage.
-- Notches at the outside corner in the TL and TR pane positions are normal. They should not appear at any corner in the BL and BR pane positions.
All 3 of the S/S's shown/linked in this thread so far all appear OK. But I've seen quite a few S/S's with trimmed selvage on the market. Because of the wide selvage, it's an old trick used to remove hinge marks and edge faults. The Scott catalog gives you approximate dimensions that are also helpful.
Enjoy your new acquisition!

k