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| Start / | Knowledge / | Separation Methods / |
| Accidentals | Changes | Designs | Differences | Errors | Fakes | Kinds | Mistakes | Parallel Issues | Printers Waste | Safety Measures | Quality |
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Knowledge / Separation Methods / Perforations / Safety Measures |
Perforation Safety Measure: safety measures made as perforation |
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Elliptical Perforation: perforation with an arch-shaped hole to avoid forgeries (syncopated perfs) |
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