# Relationship history for MSHA mine 1513924

Current hierarchy: **Gray Letcher-David Browning → D & L Coal Company → No 1 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** D & L Coal Company → No 1 Mine; 1983-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gray Letcher-David Browning Et Al → No 1 Mine; 1983-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gray Letcher-David Browning Et Al → D & L Coal Company; 1983-02-01 to current/open; source msha-controller-operator-history