Or PURLs in general, the concept for which was developed in 1995, per https://en.m.wikipedia.org/wiki/Persistent_uniform_resource_...

Nor to the Purl programming language: https://esolangs.org/wiki/Purl

I wonder if Yarn will support PURLs. ;)

I remember when purl.org namespace URIs where the thing for RSS 1.0 modules. 25 years ago,

Where can I read more about this?

We maintain the spec at https://github.com/package-url/purl-spec

And the new thing, working towards making it a real standard with Ecma https://tc54.org/purl/ ... :)

Not at all related. Just nicknamed the same.