# Relationship history for MSHA mine 1515876

Current hierarchy: **Fultz O H → Unity Fossil Fuel Inc → Dunigan Branch**

- 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:** Unity Fossil Fuel Inc → Dunigan Branch; 1987-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Fultz O H Et Al → Dunigan Branch; 1987-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Fultz O H Et Al → Unity Fossil Fuel Inc; 1987-01-01 to current/open; source msha-controller-operator-history