Question on URI Query Strings

[eluser]jamie young[/eluser]
If I understand correctly, by default CI has query strings disabled by default, preferring you to use something like http://domain.com/class/function/id. If I want to use something like http://domain.com/class?product=2 I would need to set enable_query_strings to TRUE in config.php and do something like http://domain.com/index.php/c=class&m=method&product=2.

I have noticed you can get around this if you have 2 query strings in your URL though.

Example. If I do http://domain.com/login?.done=http://google.com I get a 404, page not found, however if I do http://domain.com/login?.done=http://google.com&a the page displays properly and if I dump out $_REQUEST it will show _done and a.

Is this a feature I have not read about? or should that not be working w/out enable_query_strings set to TRUE?