S10 (UPU standard)

The UPU S10 standard defines a system for assigning 13-character identifiers to international postal items for the purpose of tracking and tracing them during shipping.

[1]: 3 With increased liberalization and the possibility of multiple postal services operating in the same country, the use of country codes to designate the postal service is a problem.

To solve this, each country has a designated postal service that controls all S10 identifiers from that country; any competing postal services will have to cooperate with the designated owner.

The organization assigned by the UPU member country shall manage the issue and use of S10 identifiers, among all the operators under the authority of that UPU member country, in such a way as to ensure that no S10 identifier is reused within a period of 12 calendar months.

The identifiers consist of a two-letter service indicator code, an eight-digit serial number (in the range 00000000 to 99999999), a single check-digit, and a two-letter ISO country code identifying the issuing postal administration's country.

The 13-character identifier for a package. It starts with the service indicator for registered mail ("RR"), followed by an 8-digit serial number (28704377), the check-digit (5) and the two-letter ISO country code for the issuing country, India ("IN")