# Relationship history for MSHA mine 4703933

Current hierarchy: **Robert M Frey → Frey's Trucking → Frey's Sand Plant**

- 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:** Frey's Trucking → Frey's Sand Plant; 2023-01-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert M Frey → Frey's Sand Plant; 2023-01-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert M Frey → Frey's Trucking; 2023-01-22 to current/open; source msha-controller-operator-history