# Relationship history for MSHA mine 4406699

Current hierarchy: **Combs Virgil & Max → Mountain Rock Products Company → Independence Quarry**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Mountain Rock Products Company → Independence Quarry; 1992-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Combs Virgil & Max Et Al → Independence Quarry; 1992-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Combs Virgil & Max Et Al → Mountain Rock Products Company; 1992-06-01 to current/open; source msha-controller-operator-history