How use route in Codeigniter

[eluser]weboap[/eluser]
http://ellislab.com/codeigniter/user-gui...uting.html

"Typically there is a one-to-one relationship between a URL string and its corresponding controller class/method. The segments in a URI normally follow this pattern:
example.com/class/function/id/

In some instances, however, you may want to remap this relationship so that a different class/function can be called instead of the one corresponding to the URL."

mean the controller "bai-vet-12-abc" need to exist???!! , you can check " _remap " but i don't think its gonna do it either.
I'm interested too to see if somebody have any idea....