Ahh, that is because that isn't a valid URI - it is an IRI. The space of IRI implementations is quite sparse, mostly limited to browsers (and often rather spot

Ahh, that is because that isn't a valid URI - it is an IRI. The space of IRI implementations is quite sparse, mostly limited to browsers (and often rather spotty within the browsers as well). So a page hyperlink or paste into a browser bar will turn it into a URI behind the scenes, but it is unlikely another program or script will handle them. In fact, I believe WHATWG defines that hyperlinks are URI, not IRI - so the generated HTML in this case by HN is not valid. IRI are of dubious value - they exist in a space where users are expected to understand and evaluate the legitimacy of an identifier by sight. That said, this is about the best we have for web domains, so (for example) I think all major browsers do render internationalized domain names in their address bar.