# Relationship history for MSHA mine 1401546

Current hierarchy: **Darwin  Knox → Knox Sand Company → Knox Sand Company**

- 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:** Darwin  Knox → Knox Sand Company; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Knox Sand Company → Knox Sand Company; 1991-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Darwin  Knox → Knox Sand Company; 1991-03-01 to current/open; source msha-controller-operator-history