The URL format in detail

The boing program itself has the ``address''

    http://kugelbus.cs.tu-berlin.de:6666/juttacgi/boing.cgi

What does that mean?

http is the protocol you use to access the whole document;
kugelbus.cs.tu-berlin.de:6666 is the domain name of a WWW server I run on my machine, which lives in the domain of the computer science department at the technical university of Berlin, Germany;
my name is Jutta, and I've configured my WWW server to allow execution of the scripts in my cgi-bin directory; this directory is addressed by the ``logical path name'' /juttacgi. There's no physical directory of that name, but a line in the http server's configuration file tells it to translate requests to /juttacgi to something else that does exist.
Finally, boing.cgi is the file name of the executable in that directory.

When I'm using boing, I add three more components to this pathname:

The name of the audio file from my boing directory that I want played, e.g., weeek.au;
Optionally, the absolute logical pathname of the image that boing redirects the server to; e.g, /~jutta/ht/orange.gif;
Optionally, a comment that I want output by the server, e.g., Hello?.

I place the audio file and the image path in the PATH_INFO component, and the comment in the QUERY_STRING. The result looks like this:

  http://kugelbus.cs.tu-berlin.de:6666/juttacgi/boing.cgi/weeek.au/~jutta/ht/orange.gif?Hello