# Relationship history for MSHA mine 3303887

Current hierarchy: **Gadd William → Blue Line Coal Company Inc → Tappan 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:** Blue Line Coal Company Inc → Tappan Mine; 1981-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gadd William → Tappan Mine; 1981-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gadd William → Blue Line Coal Company Inc; 1981-11-01 to current/open; source msha-controller-operator-history