# Relationship history for MSHA mine 1201871

Current hierarchy: **Donnetta R  Domeika → D Robertson Gravel Co Inc → D Robertson Gravel Co Inc**

- 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:** Donald R  Robertson et al → D Robertson Gravel Co Inc; 1950-01-01 to 2016-03-19; source msha-controller-operator-history
- **operator_operates_mine:** D Robertson Gravel Co Inc → D Robertson Gravel Co Inc; 1981-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald R  Robertson et al → D Robertson Gravel Co Inc; 1981-11-01 to 2016-03-19; source msha-controller-operator-history
- **controller_controls_mine:** Donnetta R  Domeika → D Robertson Gravel Co Inc; 2016-03-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donnetta R  Domeika → D Robertson Gravel Co Inc; 2016-03-20 to current/open; source msha-controller-operator-history