# Relationship history for MSHA mine 0503181

Current hierarchy: **Mc Kenzie Ron → Industrial Company → Federal Oil Shale Lease-Tract C-A**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Industrial Company → Federal Oil Shale Lease-Tract C-A; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mc Kenzie Ron → Federal Oil Shale Lease-Tract C-A; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mc Kenzie Ron → Industrial Company; 1978-03-09 to current/open; source msha-controller-operator-history