url rewriting - general letters

how should i format urls special/international characters?

currently i try urls "look good", that:

www.myhost.com/this test, know how?

is converted to:

www.myhost.com/this_is_a_test_do_you_know_how

i know general letters converted ( = ue, = ae, = aa), characters removed. i whole i try url feeling "good", nonetheless stupid?

but i chinese, japanese, arabian letters zero the western ascii format?

i unequivocally don't thought rewriting url conjuration codes, right i only middle unparalleled id url contains too "non convertable" characters.