# Relationship history for MSHA mine 1401633

Current hierarchy: **Dennis R  York → Drysandco Sand & Maintenance → Drysandco**

- 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

- **operator_operates_mine:** Drysandco Sand & Maintenance → Drysandco; 2004-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dennis R  York → Drysandco; 2004-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dennis R  York → Drysandco Sand & Maintenance; 2004-04-01 to current/open; source msha-controller-operator-history