# Relationship history for MSHA mine 2104092

Current hierarchy: **Tom  Chard; Dan  Chard → Chard Grading & Excavation LLC → #4 Portable Screener & Wash 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Tom  Chard et al → #4 Portable Screener & Wash Plant; 2020-01-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Chard Grading & Excavation LLC → #4 Portable Screener & Wash Plant; 2025-03-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tom  Chard et al → Chard Grading & Excavation LLC; 2025-03-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dan  Chard et al → Chard Grading & Excavation LLC; 2025-03-21 to current/open; source msha-controller-operator-history