[ccp4bb] shape complementarity

[Francois Berenger]

Hello,

After following the discussion on
"[ccp4bb] shape complementarity between protein and DNA surface",
is there someone here able to explain simply what the SC software
of CCP4 is calculating?
I mean, is there some intuitive/easy to understand explanation of what 
SC is calculating?

I know I should read the corresponding paper, but I'd like
someone to enlighten me before so I have better chances of understanding 
the article.

Thanks,
Francois.