Does google document these, and other URL parameters, anywhere?

It was surprisingly hard to learn about &hl=en to change almost any google product language to english, or any other language code. Indispensable if you're in a region that google autodetects as a language you don't know.

Tangential, but Firefox still supports "search engine" as a bookmark with SHORTCUTURL (as in a Netscape bookmark file). I managed to come up with the following hybrid search engine/bookmarklet, to get archive.md of paywalled articles:

  javascript:{ 
    param='%s'; 
    if (param=='%' + 's') {
      /* bookmarklet clicked */
      window.location.href = 'https://archive.md/oldest/' + window.location.href ;
    } else if (param =='') {
      /* called without argument */
      window.location.href = 'https://archive.md/oldest/' + window.location.href ;
    } else {
      /* called with a parameter*/
      window.location.href = 'https://archive.md/oldest/' + param ;
    };
  }

Copy-paste it as a bookmark URL, and set up a keyword 'ar' or what you want.

It supports 3(!) different usages at once. When you are at paywalltimes.com/article you can use it as a bookmarklet, and click on it with mouse. Or you can write 'ar' in the URL bar, and hit enter. Or, if you are not on paywalltimes.com/article, you can write 'ar paywalltimes.com/article' and hit enter (even on a newtab).

It's probably not much better than separate entries for each use cases. Also I don't even use Firefox, and Edge doesn't support bookmarks with shortcuts with parameters anymore, even when imported from Firefox. Anyway, I just shared it, maybe someone finds the template usable for something.