# Relationship history for MSHA mine 4702515

Current hierarchy: **Milton D  Ostermann → Ostermann Sand & Gravel Inc → Johnson Pit**

- 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:** Ostermann Sand & Gravel Inc → Johnson Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Milton D  Ostermann → Johnson Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Milton D  Ostermann → Ostermann Sand & Gravel Inc; 1950-01-01 to current/open; source msha-controller-operator-history