CSV++ (CSV Plus Plus): Extension to RFC 4180 for Hierarchical Data

This document specifies CSV++ (CSV Plus Plus), an extension to the Comma-Separated Values (CSV) format defined in RFC 4180. CSV++ adds support for repeating fields (one-to-many relationships) and hierarchicalcomponent structures while maintaining backward compatibility with standard CSV parsers. The extension uses declarative syntax in column headers to define array fields and nested structures, enabling representation of complex real-world data while preserving the simplicity and human-readability of CSV.