# Relationship history for MSHA mine 3303145

Current hierarchy: **Poling H W → Walwood Coal Company → Walwood 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:** Poling H W → Walwood Strip; 1973-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Walwood Coal Company → Walwood Strip; 1974-10-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Poling H W → Walwood Coal Company; 1974-10-15 to current/open; source msha-controller-operator-history