Original: In some cases, for instance the Penny Reds of Great Britain and modern United States plate number coils, the plate numbers appear in the stamps themselves, but the more common practice is to include the number in the margin of each sheet, frequently alongside the name of the printer.
Simplified: Sometimes the plate numbers appear in the stamps themselves, but the more common practice is to include the number in the margin of each sheet, frequently alongside the name of the printer.