# Relationship history for MSHA mine 1507344

Current hierarchy: **Clark Billy Joe → Triad Coal Corp → No 2 Surface**

- 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:** Clark Billy Joe → No 2 Surface; 1974-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Triad Coal Corp → No 2 Surface; 1974-09-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clark Billy Joe → Triad Coal Corp; 1974-09-23 to current/open; source msha-controller-operator-history