# Relationship history for MSHA mine 4002956

Current hierarchy: **Dan  Chambers → Wash Ridge Coal Company Inc → Old Standard**

- 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

- **controller_controls_mine:** Dan  Chambers et al → Old Standard; 1977-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Wash Ridge Coal Company Inc → Old Standard; 1987-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dan  Chambers et al → Wash Ridge Coal Company Inc; 1987-08-01 to current/open; source msha-controller-operator-history