# Relationship history for MSHA mine 1510411

Current hierarchy: **Simpson Waldo H → Simpson & Brock Coal Company Inc → No 1**

- 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

- **controller_controls_mine:** Simpson Waldo H → No 1; 1974-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Simpson & Brock Coal Company Inc → No 1; 1977-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Simpson Waldo H → Simpson & Brock Coal Company Inc; 1977-05-01 to current/open; source msha-controller-operator-history