Perf shift

A perf shift is exactly that. To count as a freak and not an error, The shift should be significant, admittedly an imprecise term. Slight shifts are just bad stamp production with some printers being known for doing a bad job at perforation. So, the more that perfs are shifted, the better. Some collectors prefer the shift being strong enough that inscriptions are moved to the other side of a stamp.  File:US perf shift.jpg|US plate block with perf shift. 

[[Category:P]]