Stréss test

In a recent post languagehat reminded readers that there is no accent diacritic in the spelling of Remy de Gourmont. He found that the Wikipedia page used one in the title and in the URL.

His reader Trey Jones rushed right over and fixed it.

So no now there are two pages on Wikipedia.

One URI with an accent:
http://en.wikipedia.org/wiki/Rémy_de_Gourmont
where readers are redirected from here.

One URI without:
http://en.wikipedia.org/wiki/Remy_de_Gourmont

Identical pages. Both with a note early in the entry, explaining that the spelling with the accent is incorrect, although very common and used by Ezra Pound in translations of his work. Ezra was so damn pretentious.

But wait. You can use diacritics in URIs? Has that always been true? I know that you have to use Roman characters, but diacritics are allowed to float around? If you know the answer maybe you'll also be able to explain to me the Ven diagram of Uniform Resource Identifiers/Locators/Names.