Polish PRNG number
The number identifying a named geographic object in the Polish register of geographical names, kept by the head office of geodesy and cartography.
The register is maintained by the Surveyor General of Poland at GUGiK, the mapping authority, under a 2021 regulation. It is a different body from GUS, which runs the territorial register, and the two number things separately.
The register is not a settlement list. It holds about 271,000 named objects, roughly half of them settlements and half physiographic features such as hills, woods, fields and rivers, along with Polish-language names for places abroad.
A plain number with no padding and no segments, running from 2 upward and currently reaching six digits. Aleksandrow Kujawski is 402, Brok 168371. Settlements and physiographic objects draw from one shared counter and never collide, which is why the length varies with when an object was registered rather than with what kind it is. Values will pass into seven digits, so a six-character column will eventually reject valid numbers.
The regulation calls the identifier unique and unchanging, and the register bears that out: an object keeps its number through a renaming and through a change of type, and a number released by a deletion is not issued again.
The register also stores the Polish SIMC code for a settlement, marked as an external identifier from another authority. The two never coincide, so neither can be derived from the other.