# Relationship history for MSHA mine 4703867

Current hierarchy: **Tony  Thier → BARD Materials → Portable Screen and Screw**

- 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:** Dennis J  Thier et al → Portable Screen and Screw; 1950-01-01 to 2014-03-02; source msha-controller-operator-history
- **controller_controls_mine:** Tony  Thier → Portable Screen and Screw; 2014-03-03 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** BARD Materials → Portable Screen and Screw; 2020-04-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tony  Thier → BARD Materials; 2020-04-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dennis J  Thier et al → BARD Materials; 2020-04-21 to 2014-03-02; source msha-controller-operator-history