There are many different numbering schemes for assigning numbers to entities. These generally require an agreed set of rules, or a central coordinator.
Numbering schemes include:
The E.164 numbering plan for telephone numbers, including:
... a "caturtitatpurusha" (caturti refers to the fourth case--that is, the dative). Incidentally, "tatpurusha" is a tatpurusha ("this man"--meaning someone's agent), while ...