# Relationship history for MSHA mine 1001752

Current hierarchy: **Campbell Roger → Camco Inc → Camco Incorporated Portable Crusher**

- 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:** Campbell Roger → Camco Incorporated Portable Crusher; 1986-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Camco Inc → Camco Incorporated Portable Crusher; 1986-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Campbell Roger → Camco Inc; 1986-09-01 to current/open; source msha-controller-operator-history