# Relationship history for MSHA mine 4607068

Current hierarchy: **Occidental Petroleum Corp → Twin-Branch Coal Company → 20-D Mine**

- 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

- **operator_operates_mine:** Twin-Branch Coal Company → 20-D Mine; 1986-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Occidental Petroleum Corp → 20-D Mine; 1986-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Occidental Petroleum Corp → Twin-Branch Coal Company; 1986-05-01 to current/open; source msha-controller-operator-history