Interestingly, the canonical link to that page is actually: https://www.w3.org/Provider/Style/URI

"You may not be using HTML for that page in 20 years time, but you might want today's links to it to still be valid. The canonical way of making links to the W3C site doesn't use the extension."

I am constantly surprised by how difficult many static site generators make it to create URLs of this format (notice no trailing slash, before you tell me about the "Pretty URLs" options in most software).

Ha! How ironic that (in part bc on phone and hasty) I grabbed the wrong URL.