{"id":"upu-s10-validate","version":"1.0.0","description":"Validate a 13-char UPU S10 postal identifier's weighted mod-11 check digit, split service indicator and country.","supported_operations":["validate a upu s10 tracking number","check digit for an international postal item","is this tracking number valid s10","split a postal tracking number into service indicator and country","verify an ems or registered mail barcode checksum","s10 postal identifier check digit calculator"],"unsupported_operations":["a live UPU or carrier tracking-status lookup","decoding the service indicator to a human-readable mail class","validating a domestic (non-S10) tracking number format"],"semantics":["item_id is taken exactly as given: no trimming, no case folding. Length != 13 returns reason wrong_length; length 13 but not matching ^[A-Z]{2}[0-9]{9}[A-Z]{2}$ returns reason invalid_character; both leave service_indicator/serial/check_digit/country null.","service_indicator = item_id[0:2], serial = item_id[2:10], check_digit = item_id[10], country = item_id[11:13], populated once length and charset pass.","country is looked up against the pinned officially-assigned ISO 3166-1 alpha-2 list (data_version iso3166-1-2026-09-28); an unlisted code returns reason unknown_country without computing the check digit.","Weighted sum over the 8 serial digits: weight = [8, 6, 4, 2, 3, 5, 9, 7]. remainder = sum mod 11; expected check digit is 5 when remainder is 0, 0 when 11-remainder is 10, else 11-remainder."],"limits":{"max_item_id_bytes":13},"pricing":{"status":"unpriced","charge_usd":null},"input_schema":{"type":"object","additionalProperties":false,"required":["item_id"],"properties":{"item_id":{"type":"string","minLength":1,"maxLength":13}}},"output_schema":{"type":"object","additionalProperties":false,"required":["valid","reason","service_indicator","serial","check_digit","country","data_version"],"properties":{"valid":{"type":"boolean"},"reason":{"type":["string","null"],"enum":[null,"wrong_length","invalid_character","unknown_country","check_digit_mismatch"]},"service_indicator":{"type":["string","null"],"pattern":"^[A-Z]{2}$"},"serial":{"type":["string","null"],"pattern":"^[0-9]{8}$"},"check_digit":{"type":["string","null"],"pattern":"^[0-9]$"},"country":{"type":["string","null"],"pattern":"^[A-Z]{2}$"},"data_version":{"type":"string","const":"iso3166-1-2026-09-28"}}},"examples":[{"input":{"item_id":"LT284905264NL"},"output":{"valid":true,"reason":null,"service_indicator":"LT","serial":"28490526","check_digit":"4","country":"NL","data_version":"iso3166-1-2026-09-28"}},{"input":{"item_id":"LT284905264ZZ"},"output":{"valid":false,"reason":"unknown_country","service_indicator":"LT","serial":"28490526","check_digit":"4","country":"ZZ","data_version":"iso3166-1-2026-09-28"}},{"input":{"item_id":"LT28490526NL"},"output":{"valid":false,"reason":"wrong_length","service_indicator":null,"serial":null,"check_digit":null,"country":null,"data_version":"iso3166-1-2026-09-28"}}],"execute_url":"/v1/tools/upu-s10-validate/versions/1.0.0/execute"}