# Relationship history for MSHA mine 0405015

Current hierarchy: **Muht-Hei Inc → Campo Materials Company → Campo Materials Company**

- 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:** John  Woodward → Campo Materials Company; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Woodward Sand Company Inc → Campo Materials Company; 1988-10-01 to 1990-11-25; source msha-controller-operator-history
- **controller_controls_operator:** John  Woodward → Woodward Sand Company Inc; 1988-10-01 to 1990-11-25; source msha-controller-operator-history
- **operator_operates_mine:** Campo Materials Company → Campo Materials Company; 1990-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Muht-Hei Inc → Campo Materials Company; 1990-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Muht-Hei Inc → Campo Materials Company; 1990-11-26 to current/open; source msha-controller-operator-history