# Relationship history for MSHA mine 1201526

Current hierarchy: **Sexton Walter → Gatewood Mining Company → Birdsong Strip**

- 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

- **controller_controls_mine:** Sexton Walter → Birdsong Strip; 1976-02-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gatewood Mining Company → Birdsong Strip; 1976-04-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sexton Walter → Gatewood Mining Company; 1976-04-15 to current/open; source msha-controller-operator-history