Ask HN: Why are URNs not more popular?

I'm working on i18n of an API for a customer now. It's a domain where one needs to refer to phone numbers, bank accounts, National Identity Numbers, business / legal entity organization numbers etc; in short, IDs in misc. national and international registries.

URN should be perfect for this; I would expect to do the i18n by replacing a Norwegian account number "12345678902" with "urn:bban:NO:12345678902", or a Danish company number "987322431" with "urn:business:DK:CRV:987322431".

However, the list of URN namespaces is very lacking. I'd expect to at least see "urn:msisdn:"; or "urn:nin:DK:..." for Danish national identity numbers. But it's not there.

What I see looking around is a lot of home made solutions that make inferences about ID spaces based on "country" that usually holds but not always; or solutions coming from the XML world that seem very complicated to figure out (like ISO 6523 which declares '0037' for the Finnish company registry, and the syntax around it is XML or home-grown). URN would have been such a simple and nice solution. Why has it not catched on?

URN are the "missing link" in the semantic web. If you look at examples where somebody writes an RDF file they typically use identifiers like

which are fine for cases where you want to publish the data on the web but not for the much more common case of "our own private data".

It is straightforward in principle to use URNs, but it is not easy to find examples or discussion of best practices with URNs. For one thing you can always write

so you can generate as many unique ids as you need.

Why restrict to URN when you can use a URI that looks similar to a URL but doesn't have to be accessible. I've used URIs for partner supplied identifiers. They're also used with GraphQL as resource ids.

For widely standardized things URNs make complete sense e.g. ISBN for books.

I don't really want to classify objects.

I want to refer to a registration in a registry. Objects can of course be regidtered many places for many reasons but that is not my concern here.

As long as I can serialize the tuple (registry-somone-made, id-in-that-registry) in a standard and readable way that would be a huge step forward

The specific reference is to the essay "The Analytical Language of John Wilkins", in which Borges likens an taxonomy proposed by Wilkins to a (almost certainly fictitious) Chinese encyclopedia which groups animals into fourteen categories:

> (a) those that belong to the Emperor, (b) embalmed ones, (c) those that are trained, (d) suckling pigs, (e) mermaids, (f) fabulous ones, (g) stray dogs, (h) those that are included in the present classification, (i) those that tremble as if they are mad, (j) innumerable ones, (k) those drawn with a very fine camelhair brush, (l) others, (m) those that have just broken a flower vase, (n) those that look like flies from a long way off.