View source for UPU S10 Standard

[[zh:万国邮联S10标准]]
UPU S10 Standard defined a system distributing an 13-digit identifying code for mail pieces in order to trace and follow them in the entire transit process.

With increased liberalisation and the possibility of multiple postal services operating in the same country, the use of country codes to designate postal services became an issue. To solve this problem, each country/region has a designated postal service for controlling all S10 identifiers from that country/region; any competing postal service must co-operate with the designated owner. The organisation assigned by the UPU Member State shall manage the issuance and use of S10 identifiers between all operators under the jurisdiction of that UPU Member State to ensure that there is no duplication of S10 identifiers within a 12 calendar month period. A period of 24 calendar months or more is recommended.

=== Format ===
The identifier consists of a two-letter service indicator code, an eight-digit serial number (ranging from 000000000 to 99999999), a check digit, and a two-letter [[List of Code for Countries and Regions|ISO country/area code]] that identifies the country/area in which the issuing postal administration is located.
{| class="wikitable"
|+S10 Format
!1
!2
!3
!4
|-
|AA
|00000000
|9
|BB
|-
| colspan="4" |
# service indicator code
# serial number
# check digit
# [[List of Code for Countries and Regions|ISO country/area code]]
|}

=== Service indicator code ===
Service codes are typically assigned and managed within each country of issue, but certain types of services and code ranges are used for all countries listed here.
{| class="wikitable"
|+
!Code
!Meaning
|-
|AA-AZ
|For domestic, bilateral and multilateral use only; Identification of RFID-tracked [[e-commerce]] items
|-
|BA-BZ
|For domestic, bilateral and multilateral use only
|-
|CA-CZ
|For [[Parcel Post]], the use of CZ requires a bilateral agreement. There is no need to use CV for insured parcel. However, if CV is used, it is advised to be used on insured parcel only.
|-
|DA-DZ
|For domestic, bilateral and multilateral use only
|-
|EA-EZ
|[[EMS (Express Mail Service)]]; Using EX-EZ requires bilateral agreement
|-
|GA, GD
|For domestic, bilateral and multilateral use only
|-
|HA–HZ
|[[e-commerce]] parcel; Using HX-HY requires multilateral agreement; Using HZ requires bilateral agreement
|-
|JA–JZ
|Reserved; Cannot be assigned as a valid service indication code
|-
|KA–KZ
|Reserved; Cannot be assigned as a valid service indication code
|-
|LA–LZ
|[[Tracked item]]. including several sub-classes; Using LZ requires bilateral agreement
|-
|MA–MZ
|[[M bag]]
|-
|NA–NZ
|For domestic, bilateral and multilateral use only
|-
|PA–PZ
|For domestic, bilateral and multilateral use only
|-
|QA–QM
|IBRS
|-
|RA–RZ
|[[Registered Mail|Registered Item]]; Using RZ requires bilateral agreement
|-
|SA–SZ
|Reserved; Cannot be assigned as a valid service indication code
|-
|TA–TZ
|Reserved; Cannot be assigned as a valid service indication code
|-
|UA–UZ
|[[Letter post]] other than LA-LZ ([[Tracked item|Tracked]]), MA-MZ ([[M bag]]), QA-QM ([[IBRS]]), RA-RZ ([[Registered Mail|Registered]]), and VA-VZ ([[Insured Mail|Insured]])
|-
|VA–VZ
|Insured item; Using VZ requires bilateral agreement
|-
|WA–WZ
|Reserved; Cannot be assigned as a valid service indication code
|-
|ZA–ZZ
|For domestic, bilateral and multilateral use only
|}