# Relationship history for MSHA mine 4201956

Current hierarchy: **Wolff Excavating Inc → Wolff Excavating Inc → Wolff Excavating Incorporated**

- 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

- **operator_operates_mine:** Wolff Excavating Inc → Wolff Excavating Incorporated; 1985-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Wolff Excavating Inc → Wolff Excavating Incorporated; 1985-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wolff Excavating Inc → Wolff Excavating Inc; 1985-09-01 to current/open; source msha-controller-operator-history