# Relationship history for MSHA mine 1511659

Current hierarchy: **Mary Helen Coal Company Inc → Danny Boy Coal Company Inc → No 2 (D)**

- 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

- **controller_controls_mine:** Mary Helen Coal Company Inc → No 2 (D); 1977-10-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Danny Boy Coal Company Inc → No 2 (D); 1978-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mary Helen Coal Company Inc → Danny Boy Coal Company Inc; 1978-11-01 to current/open; source msha-controller-operator-history