# Unified substrate MRF version ledger

`dim_substrate_mrf_version` · Provenance · status live

Substrate-wide audit chain: every fetched MRF (commercial / hospital / medicare) gets a row with content hash, raw S3 key, parser artifact hash, and first/last-seen timestamps. The provenance backbone for receipts + replay.

**Grain.** One row per (substrate, natural_key, content_sha256) observed MRF file.

Query it: `query_substrate` with `SELECT ... FROM dim_substrate_mrf_version WHERE ... LIMIT 100`; read `describe_data_source("dim_substrate_mrf_version")` first.