{"@context":"https://schema.org","@type":"DefinedTerm","name":"UPU S10 (postal tracking number)","description":"The Universal Postal Union format for international postal items: 2 service letters + 8-digit serial + 1 check digit + 2-letter ISO country code (e.g. RR\u2026GB = registered letter from the UK). Check digit: weights 8,6,4,2,3,5,9,7 over the serial, C = 11 \u2212 (sum mod 11), with 10\u21920 and 11\u21925 \u2014 the official special rules many implementations get wrong.","inDefinedTermSet":"https://trackjet.world/glossary"} Skip to content
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UPU S10 (postal tracking number)

The Universal Postal Union format for international postal items: 2 service letters + 8-digit serial + 1 check digit + 2-letter ISO country code (e.g. RR…GB = registered letter from the UK). Check digit: weights 8,6,4,2,3,5,9,7 over the serial, C = 11 − (sum mod 11), with 10→0 and 11→5 — the official special rules many implementations get wrong.

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