Extended Betza notation

Basic Betza notation combines elementary movement patterns and restrictions. Extended Betza notation, also called XBetza, enlarges that language for pieces whose movement cannot be reduced to one leap or slide.

Its central device is chaining: one move can be divided into several conceptual stages, or legs. Each leg can require an intermediate square to be empty, occupied by a friendly piece, or occupied by an enemy. It may also pass, capture, swap, or place a piece along the route.

These conditions can model hoppers that need a hurdle, multi-stage captures, moves affecting more than one square, and special cases. Examples include castling, in which king and rook move as one turn, and en passant, where a pawn captures an opposing pawn that has just advanced two squares and removes it from an adjacent square. Other modifiers can restrict a power to a piece that has not moved before.

XBetza still describes movement rules, not a list of moves that were played. A concrete move uses a format such as UCI move notation. Implementations may also support different subsets, so a complex string should be read with the consuming program's documentation.