which opening book is better perfect15 or storm19.12.08?

[Uri Blass]

I guess that storm is better because it is later book but I am not sure

http://www.sedatchess.com/scct4.html

I wonder also how people decide about the moves that are prefered in the opening books and if the moves are based on hours of analysis with rybka.

Last question:What is the meaning of the Fact column in the Storm2.1's book

usually perfect15.ctg has simply 0 there but Storm2.1's book has numbers.

Does bigger number mean better move.
Is it learning value that is changed after a win or a loss and how it is changed?

I wonder if it is a good idea to prefer moves with higher value in correspondence games.

Uri

[F. Bluemers]

I wonder also how people decide about the moves that are prefered in the opening books and if the moves are based on hours of analysis with rybka.

All moves?
Those books will be pretty small then