# Relationship history for MSHA mine 4703893

Current hierarchy: **Kohner Holding Company → Wabasha Sand & Gravel → Portable Plant 3**

- 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

- **controller_controls_mine:** Robert S  Kohner et al → Portable Plant 3; 1950-01-01 to 2023-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Wabasha Sand & Gravel → Portable Plant 3; 2021-04-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert S  Kohner et al → Wabasha Sand & Gravel; 2021-04-21 to 2023-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Steven  Kohner et al → Wabasha Sand & Gravel; 2021-04-21 to 2023-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Kohner Holding Company → Portable Plant 3; 2024-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kohner Holding Company → Wabasha Sand & Gravel; 2024-01-01 to current/open; source msha-controller-operator-history