UV filter question

G'day All,
Just wondering if someone could tell me the difference between a UV[N] and a UV[0] filter? They are both identical as far as I can tell, except for the name on the box. Any suggestions?
Tristan
Just wondering if someone could tell me the difference between a UV[N] and a UV[0] filter? They are both identical as far as I can tell, except for the name on the box. Any suggestions?
Tristan