Independent This document defines MaSON (Markdown Structured Object Notation), a lightweight data serialization format that maps standard Markdown syntax trees into structured key-value objects. MaSON is designed to maximize human readability and LLM token efficiency by eliminating bracket-based nesting and strict indentation rules. This updated specification introduces "Compact Mode" optimized for extreme token density, support for multi-line string encapsulation, and mixed-type array isolation via forced brackets.