# Relationship history for MSHA mine 1512155

Current hierarchy: **Vaughan C Douglas → Vaughan Brothers Inc → No 1 Surface 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:** Vaughan Brothers Inc → No 1 Surface Mine; 1979-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vaughan C Douglas → No 1 Surface Mine; 1979-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vaughan C Douglas → Vaughan Brothers Inc; 1979-10-01 to current/open; source msha-controller-operator-history