A recent purchase was this Scott 130, ACSC 146 Ash Imprint Block of 8:
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In the row between the stamps, I'm seeing what I've always referred to as Guide Dots. They are located between each stamp on that row (circled in black):
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I'm trying to figure out these other dots, located in the bottom margin below the Ash Imprint. the arrows are pointing them out. They are much larger than the Guide Dots above, and they are right on the perforation area, so might not be normally seen:
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Are these just more guide dots, or positioning dots? In the ACSC King George VI catalog, there is mention of Perforation Guide Marks, and Perforation Pips, but the timing of these seems to be much later than 1932.