# Relationship history for MSHA mine 1201687

Current hierarchy: **Day John D → John Day Coal Company Inc → John Day Coal Co Inc Strip**

- 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:** John Day Coal Company Inc → John Day Coal Co Inc Strip; 1978-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Day John D → John Day Coal Co Inc Strip; 1978-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Day John D → John Day Coal Company Inc; 1978-12-01 to current/open; source msha-controller-operator-history