pnn

https://github.com/sashite/pnn.rb

A clean, immutable Ruby interface for working with piece identifiers in PNN format. PNN provides a consistent and rule-agnostic notation for representing pieces in abstract strategy board games like chess, shogi, and xiangqi. Features include state modifiers for enhanced/diminished/intermediate pieces, ownership changes, and comprehensive validation. Perfect for game engines, analysis tools, and educational applications.