Can someone explain me usage of opening book like the one available from XG site ? Looking
through the description of the XG opening book format I see no moves in positions. Only position
with rolled out equities. So to use to find best play in position one would have to run through ALL legal plays, lookup resulting position and get equity and pick the move with resulting position having highest overall equity ?! Seems not efficient to me. Why not book with stored at position under consideration equities of resulting positions for top moves ? Maybe I miss some understanding ?