What is the appendix index?

The appendix index is the controlled reference layer between report-facing structures and sealed artifacts.

It identifies which underlying artifacts support a report section, aggregate value, table, map, or reproducibility statement. The appendix index allows SDX to keep the main report or report-data package readable while preserving access to the full machine-verifiable evidence base.

This prevents two opposite failures. The report does not become overloaded with every raw value, but it also does not become detached from the underlying evidence. Instead, selected decision-facing values can point to complete sealed artifacts through structured references.

In SDX, the appendix index is especially important when a domain contains many units, zones, rows, or geospatial outputs. The report may surface the assertion-relevant structure, while the appendix index preserves the path back to the complete sealed material.