# Relationship history for MSHA mine 1001897

Current hierarchy: **Clifford  Everman → Apple Sand & Gravel → Portable Screen Plant**

- 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:** Clifford  Everman → Portable Screen Plant; 1988-07-11 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Apple Sand & Gravel → Portable Screen Plant; 1993-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clifford  Everman → Apple Sand & Gravel; 1993-12-01 to current/open; source msha-controller-operator-history