# Relationship history for MSHA mine 1512775

Current hierarchy: **Epling Walter Ben & Michael R → Elkhorn Drilling Company → Elkhorn Drilling**

- 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:** Elkhorn Drilling Company → Elkhorn Drilling; 1981-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Epling Walter Ben & Michael R → Elkhorn Drilling; 1981-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Epling Walter Ben & Michael R → Elkhorn Drilling Company; 1981-03-01 to current/open; source msha-controller-operator-history