[Search-l] Which does the figure next to each URL mean?

[Grub Nutch]

Hi.

When you search something at WikiaSearch (e.g
http://alpha.search.wikia.com/search/search-a.html#paris), there's a
figure next to each URL:

http://paris-maniak.site.voila.fr/ - Cached - 8.37

Which does "8.37" mean? It's a relevance factor? Most of times it's
descendant, but sometimes there's a higher value among others.

BTW, is there any webpage explaining the parameters of the page where
this value is calculated (segment, boost, score, ...)?

Thank you very much.