What do the perforation numbers in the catalogue mean?
Perforations are the holes along the stamp’s edge used to help separate stamps from one another. They are measured by counting the number of holes in 2 centimeters – therefore a stamp that is “Perf 11” has 11 holes every two centimeters. Various gauges are available to measure perforations. They are easy to use. You simply find the marks on the gauge which line up with the holes on the stamp. Sometimes the perforation count of a stamp is different horizontally and vertically – in this case the horizontal measure is given first – as in “Perf 11 X 10.
