# Relationship history for MSHA mine 1508758

Current hierarchy: **Dehart Virgil → D D & S Coal Company → No 1 Surface**

- 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:** D D & S Coal Company → No 1 Surface; 1975-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dehart Virgil Et Al → No 1 Surface; 1975-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dehart Virgil Et Al → D D & S Coal Company; 1975-08-01 to current/open; source msha-controller-operator-history