# Relationship history for MSHA mine 3602012

Current hierarchy: **Drebitko Andrew → Ad Coal Company → A D Prep**

- 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:** Strohecker Coal Company → A D Prep; 1950-01-01 to 1984-06-28; source msha-controller-operator-history
- **controller_controls_mine:** Strohecker Joel → A D Prep; 1950-01-01 to 1984-06-28; source msha-controller-operator-history
- **controller_controls_operator:** Strohecker Joel → Strohecker Coal Company; 1950-01-01 to 1984-06-28; source msha-controller-operator-history
- **operator_operates_mine:** Ad Coal Company → A D Prep; 1984-06-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Drebitko Andrew → A D Prep; 1984-06-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Drebitko Andrew → Ad Coal Company; 1984-06-29 to current/open; source msha-controller-operator-history