# Relationship history for MSHA mine 1510123

Current hierarchy: **Nixon Dean → Tenkiller Mining Services Inc → Prep Plant**

- 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:** Texas Pioneer Coal Company → Prep Plant; 1976-11-01 to 1980-06-08; source msha-controller-operator-history
- **controller_controls_mine:** Pioneer Corp → Prep Plant; 1976-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pioneer Corp → Texas Pioneer Coal Company; 1976-11-01 to 1980-06-08; source msha-controller-operator-history
- **operator_operates_mine:** Tenkiller Mining Services Inc → Prep Plant; 1980-06-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Nixon Dean → Prep Plant; 1980-06-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nixon Dean → Tenkiller Mining Services Inc; 1980-06-09 to current/open; source msha-controller-operator-history