# Relationship history for MSHA mine 3503903

Current hierarchy: **Ron  Robinson Jr; Ryan C  Clark → 4-R Equipment LLC → Portable 2020**

- 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:** Ron  Robinson Jr → Portable 2020; 1998-09-01 to 2016-04-12; source msha-controller-operator-history
- **controller_controls_mine:** Ron  Robinson Jr et al → Portable 2020; 2016-04-13 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** 4-R Equipment LLC → Portable 2020; 2020-05-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ron  Robinson Jr et al → 4-R Equipment LLC; 2020-05-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ryan C  Clark et al → 4-R Equipment LLC; 2020-05-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ron  Robinson Jr → 4-R Equipment LLC; 2020-05-06 to 2016-04-12; source msha-controller-operator-history