Remap or URI Routing or What?

[eluser]JanDoToDo[/eluser]
thanks again! What would I do if I wanted to remove the additional parameters from the uri if they are not needed? i.e. if i have this uri /communities/the-uk-massive/join/extra1/extra2

Can i automatically remove the extra 1 and 2 or would i have to test and then redirect back to the page?

Also, is there a preference for search engines whether i should show a 404 or just show the standard overview page if a method doesnt exist?