# Relationship history for MSHA mine 4002493

Current hierarchy: **Asbury Harold F → Asco Energy Construction Company Inc → Asco Energy Const Co 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Asco Energy Construction Company Inc → Asco Energy Const Co Surface; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Asbury Harold F Et Al → Asco Energy Const Co Surface; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Asbury Harold F Et Al → Asco Energy Construction Company Inc; 1979-01-01 to current/open; source msha-controller-operator-history