Danish municipality code
The four-digit code identifying a Danish municipality, assigned by the Ministry of the Interior under the civil registration law.
The code is assigned by the Ministry of the Interior and is also called an authority code inside the civil registration system. Statistics Denmark, the data authority and the building register all reuse it, which is why it is often attributed to them instead.
Four digits, and the leading zero is part of the canonical form: the official list runs from 0101 to 0860, and Aabenraa is 0580. The first two digits reflect the historical county grouping, the last two the municipality within it.
The same code is often written without its leading zero as three digits, and Greenland's codes are natively three, so a three-digit value is not necessarily wrong. Stored as a number, though, 0101 stops matching the register.
The 98 municipalities date from the 2007 reform, which cut them from 271 and reassigned every code, so a value from before 2007 belongs to a scheme that no longer exists.
