# Relationship history for MSHA mine 3609742

Current hierarchy: **Richard L  Johnson → Richard L. Johnson → Johnson Stone Portable**

- 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:** Richard L. Johnson → Johnson Stone Portable; 2009-04-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Richard L  Johnson → Johnson Stone Portable; 2009-04-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard L  Johnson → Richard L. Johnson; 2009-04-15 to current/open; source msha-controller-operator-history