# Relationship history for MSHA mine 4401903

Current hierarchy: **Boyd Leon → Six B 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Stiltner & Boyd Coal Company → No 1 Mine; 1950-01-01 to 1974-07-15; source msha-controller-operator-history
- **controller_controls_mine:** Stiltner & Boyd Coal Company → No 1 Mine; 1950-01-01 to 1974-07-15; source msha-controller-operator-history
- **controller_controls_operator:** Stiltner & Boyd Coal Company → Stiltner & Boyd Coal Company; 1950-01-01 to 1974-07-15; source msha-controller-operator-history
- **operator_operates_mine:** Six B Coal Company → No 1 Mine; 1974-07-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Boyd Leon → No 1 Mine; 1974-07-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Boyd Leon → Six B Coal Company; 1974-07-16 to current/open; source msha-controller-operator-history