# Relationship history for MSHA mine 1519794

Current hierarchy: **Sandra  Parks → Sand Contracting LLC → Letcher 1A**

- 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

- **controller_controls_mine:** Sandra  Parks → Letcher 1A; 2016-01-18 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sand Contracting LLC → Letcher 1A; 2016-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sandra  Parks → Sand Contracting LLC; 2016-03-31 to current/open; source msha-controller-operator-history