# Relationship history for MSHA mine 3201031

Current hierarchy: **Robert L Lindberg → Northern Excavating Company → Northern Excavating Company**

- 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:** Northern Excavating Company → Northern Excavating Company; 2014-05-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert L Lindberg → Northern Excavating Company; 2014-05-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert L Lindberg → Northern Excavating Company; 2014-05-06 to current/open; source msha-controller-operator-history