# Relationship history for MSHA mine 3606817

Current hierarchy: **Nat- Industries Inc → Nat- Industries Inc → Nat Mine (Loading Dock)**

- 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

- **controller_controls_mine:** Nat- Industries Inc → Nat Mine (Loading Dock); 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nat- Industries Inc → Nat Mine (Loading Dock); 1979-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nat- Industries Inc → Nat- Industries Inc; 1979-04-01 to current/open; source msha-controller-operator-history