The server side script can do anything with that value, we can't tell you what it does without knowing the actual URL. (And even if we know it we can just guess).

But why do you want to know that? Sounds like an XY Problem to me.

Read all about GET in the HTTP 1.1 standard (p. 53) or the CGI standard.

You don't actually need the ? as "extra" data will be passed in the PATH_INFO environment var and can be retrieved and used by a CGI quite easily from there. ?& is something of a contradiction in terms although I guess most CGI parsing libs would deal with it and discard the first nameless, valueless param.

You are right, but strictly speaking it is then not a parameter of the GET call and your server must "know" that some of the info is in the path and not in the parameter list.

Try to drop the '?' in the above perlmonks URL and see what I mean.

I wonder, is '&' even allowed as part of a path?

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

Is this a common type of extension?

Hello? Of course it is a common type of extension, read the adress bar in your browser to see further examples.

Can anyone shed any light on the features of an address that may end like this?

The information is *probably* being passed to a CGI script. That script is *probably* doing something with it. The script may be in *any* languague, probably not perl. Short of hacking the server or finding out what software it is running and groking the source there is no easy way to know. If you have 1/2 a brain you can look at sequential requests and see what happens to ch= as you do different stuff. This will let you guess it's function with reasonable certainty if you are clever enough.

I have spoken to the people responsible for the maintenance of the website, who do not know.

You have spoken to the wrong people.

Is is possible this could relate to some kind of search function?

It is possible this could relate to anything. It is probably a session tracking ID or a document identifier if you want the two most common posibilities. A search string would look roughly like ?q=find%20this where you searched for "find this"