# Relationship history for MSHA mine 4607313

Current hierarchy: **Key Doug → Clell Key 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Clell Key Coal Company → No 1 (Surface); 1987-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Key Doug → No 1 (Surface); 1987-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Key Doug → Clell Key Coal Company; 1987-06-01 to current/open; source msha-controller-operator-history