A friend of mine is trying to get a Tottenham Hotspurs fansite up and running. He also made a custom 404.htm file (which appears each time a non-existing page is requested). When that page appears, in the address bar it gets like this:
/404.htm?404;theinvalidfile.html
What I want to know is how can I make the second argument (theinvalidfile.html) appear on the website? I consider myself an expert on HTML, but I have never seen anything like this...
PS: It's just a regular html page, no php, asp or anything.