# Relationship history for MSHA mine 4502910

Current hierarchy: **Simmons Charles E → Simmons Construction Inc → Simmons 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Simmons Construction Inc → Simmons Portable Crusher; 1981-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Simmons Charles E → Simmons Portable Crusher; 1981-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Simmons Charles E → Simmons Construction Inc; 1981-05-01 to current/open; source msha-controller-operator-history