This repository provides a native PHP implementation of enumeration types, offering base Enum class, EnumSet for efficient set operations, and EnumMap for mapping enum keys to values. The Enum class implements the singleton pattern for enum values, ensuring that equivalent enum values are identical instances, and includes features like lazy constant discovery, inheritance support, and proper comparison handling. The EnumSet component stands out for its innovative bit vector implementation that automatically switches between integer storage (for small sets) and binary string storage (for large sets) to optimize memory usage and performance. It provides standard set operations (union, intersection, difference, symmetric difference) through efficient bitwise operations, making it particularly valuable for applications requiring efficient set manipulation on enum values. The library is well-maintained with comprehensive test suites, benchmarks, and support for multiple PHP versions. It follows semantic versioning and includes development tools for code quality checking. While the EnumSerializableTrait provides serialization support with noted caveats, the core enum functionality is robust and suitable for use in production PHP applications requiring type-safe enumeration patterns.