# Relationship history for MSHA mine 4605050

Current hierarchy: **Campbell William A → Ace Equipment Rentals Company → Ace Surface No 4**

- 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:** Campbell William A → Ace Surface No 4; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ace Equipment Rentals Company → Ace Surface No 4; 1976-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Campbell William A → Ace Equipment Rentals Company; 1976-03-01 to current/open; source msha-controller-operator-history