URL and URI links

[Vasilii Kolobkov]

The specification has URLs for link lines.  Is that an intentional
choice over a broader URI category?

I'm thinking about using text/gemini outside Gemini protocol and would
likely use some form of URNs for links.  There is also a lovely
urn:isbn: namespace that's left behind.

I'm new around here and am sorry if that has been discussed somewhere
already.

p.s. please keep me cc'd.