# Relationship history for MSHA mine 0405793

Current hierarchy: **Nicholas J  Tonkinson → Ranch Rock → Highland 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Nicholas J  Tonkinson → Highland Plant; 2000-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ranch Rock → Highland Plant; 2009-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nicholas J  Tonkinson → Ranch Rock; 2009-10-01 to current/open; source msha-controller-operator-history