Manipulating Nutch 2.2.1 scoring system

[Vangelis karv]

It is clear that OPICScoringfilter does all the job in creating the scores for 
the urls. I just wanted to know if it is possible to implement another function 
for scoring and if there are any available on the Internet. Does anybody know 
where exactly in the code, Nutch calls that function(Generator,Fetcher,Parser)?