UCI options and commands

Options

UCI_Variant defines the chess variant.
AbsScoreRange, AbsScoreBias: see filter
MoveScoreRange defines the range of good moves in centipawns.
DepthFactor is used to modify MoveScoreRange in dependence of the depth from the root position. The effective range is calculated as MoveScoreRange * (DepthFactor / 100) ^ depth.
MultiPV defines the maximum branching factor of opening lines during book generation.
TrimFEN is true or false and defines whether the half- and fullmove counter should be trimmed from the FEN to avoid duplicates. Default value is false. If set to true the resulting book will contain incomplete FEN/EPDs that are not compatible with all EPD compatible tools.
EPDPath specifies where the opening book is stored when save is called. Default value is the relative path book.epd.

generate n is used to generate FENs. The argument n is required and specifies the depth of the book in halfmoves, e.g., generate 3. Optional arguments are movetime, depth, and perft. The optional arguments are passed to the go command when searching positions. If perft is given, all positions that are possible after n ply are generated.
filter filters the current set of positions. It performs a search on each position with the given arguments. E.g., filter depth 12 movetime 100 performs a search up to depth 12 limited to 100 milliseconds. A position is filtered out if it is outside of the range defined by [-AbsScoreRange + AbsScoreBias, AbsScoreRange + AbsScoreBias] or if there are less moves within MoveScoreRange compared to the best move than defined by MultiPV.
clear removes all FENs from the list.
size prints the number of positions in the list.
print prints the FENs.
save writes the FENs to the file specified in EPDPath