There are separate URLs for "https:" vs "http:" although they are usually the same content when both are available (although I have seen some where it isn't the same), although the compression (and some other stuff) is decided by headers. However, it might make sense to include some of these things optionally within the URL (within the authority section and/or scheme section somehow), for compression, version of the internet, version of the protocol, certificate pinning, etc, in a way that these things are easily delimited so that a program that understands this convention can ignore them. However, that might make a mess.

I had also defined a "hashed:" scheme for specifying the hash of the file that is referenced by the URL, and this is a scheme that includes another URL. (The "jar:" scheme is another one that also includes other URL, and is used for referencing files within a ZIP archive.)

> Would you also suggest I use separate URLs for HTTP/2 and HTTP/1.1? Maybe for a gzipped response vs a raw response?

The difference between HTTP/2 and HTTP/1.1 is exactly like the difference between plugging your PC in with a green cable or a red cable. The client neither knows nor cares.

> It's the same content, just supplied in a different format. It should be the same URL.

So what do I put as the URL of an MP3 and an Ogg of the same song? It's the same content, just supplied in a different format.

Then the server should supply the right format based on the `Accept` header, be it `application/rss+xml` or `application/atom+xml` or `text/xml` or `text/html`.

Even cheaper than shipping the client an XML and an XSLT is just shipping them the HTML the XSLT would output in the first place.