# Relationship history for MSHA mine 1507738

Current hierarchy: **Wolfe Industries Inc → Wolfe Industries Coal Company → Old Rev**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Ohio County Coal Inc → Old Rev; 1974-10-01 to 1981-04-01; source msha-controller-operator-history
- **controller_controls_mine:** Depp Robert R → Old Rev; 1974-10-01 to 1981-04-01; source msha-controller-operator-history
- **controller_controls_operator:** Depp Robert R → Ohio County Coal Inc; 1974-10-01 to 1981-04-01; source msha-controller-operator-history
- **operator_operates_mine:** Wolfe Industries Coal Company → Old Rev; 1981-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Wolfe Industries Inc → Old Rev; 1981-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wolfe Industries Inc → Wolfe Industries Coal Company; 1981-04-02 to current/open; source msha-controller-operator-history