# Relationship history for MSHA mine 0503280

Current hierarchy: **Mine Shaft & Tunnel Corp → Mine Shaft & Tunnel Corp → Federal Oil Shale Lease Tract Ca**

- 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

- **operator_operates_mine:** Mine Shaft & Tunnel Corp → Federal Oil Shale Lease Tract Ca; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mine Shaft & Tunnel Corp → Federal Oil Shale Lease Tract Ca; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mine Shaft & Tunnel Corp → Mine Shaft & Tunnel Corp; 1979-01-01 to current/open; source msha-controller-operator-history