# Relationship history for MSHA mine 1506983

Current hierarchy: **Combs N L → N & R Coal Company Inc → Surface Mine**

- 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:** N & R Coal Company Inc → Surface Mine; 1974-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Combs N L → Surface Mine; 1974-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Combs N L → N & R Coal Company Inc; 1974-01-01 to current/open; source msha-controller-operator-history