# Relationship history for MSHA mine 4406660

Current hierarchy: **Robray Corp → Blackwood Fuel Company Inc → No 2**

- 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:** Robray Corp → No 2; 1980-06-16 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Blackwood Fuel Company Inc → No 2; 1991-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robray Corp → Blackwood Fuel Company Inc; 1991-08-01 to current/open; source msha-controller-operator-history