# Relationship history for MSHA mine 1512698

Current hierarchy: **Boyd Chester → Boyd Coal Company Inc → No1**

- 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:** Darvin Burchett Enterprises Inc → No1; 1981-01-01 to 1982-08-23; source msha-controller-operator-history
- **controller_controls_mine:** Burchett Darvin → No1; 1981-01-01 to 1982-08-23; source msha-controller-operator-history
- **controller_controls_operator:** Burchett Darvin → Darvin Burchett Enterprises Inc; 1981-01-01 to 1982-08-23; source msha-controller-operator-history
- **operator_operates_mine:** Boyd Coal Company Inc → No1; 1982-08-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Boyd Chester → No1; 1982-08-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Boyd Chester → Boyd Coal Company Inc; 1982-08-24 to current/open; source msha-controller-operator-history