# Relationship history for MSHA mine 0202120

Current hierarchy: **Martin David W → David W Martin → Agua Fria Sand & Gravel**

- 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

- **operator_operates_mine:** David W Martin → Agua Fria Sand & Gravel; 1982-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Martin David W → Agua Fria Sand & Gravel; 1982-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin David W → David W Martin; 1982-11-01 to current/open; source msha-controller-operator-history