Comb perf

Comb perfs are where the perforation holes meet perfectly in each corner, assuming a rectangular stamp, of course.

Line perfs are where the perforation holes do not meet perfectly in the corners.

These are the result of different types of machinery and methods used to produce perfs. Some stamps come both ways with one type of perf scarcer than the other, so you should be aware of the two methods. These are usually only mentioned in specialist catalogs, though. The 1900 Switzerland UPU original issue is an example of that. Be aware that reperfing is always possible to create perf varieties or to make repairs.

 File:Switz 1930 Pro Juv blk.jpg|The block clearly shows the comb perf. File:US Lincoln Mem blk.jpg|This block clearly shows line perf. File:US Arlington blk.jpg|This block is line perfed but might be mistaken for comb perf. The perfs must meet perfectly in the corners. 

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