# Relationship history for MSHA mine 3609701

Current hierarchy: **Norman  Zimmerman → Norman Zimmerman → Norman Zimmerman Strip**

- 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:** Norman Zimmerman → Norman Zimmerman Strip; 2009-01-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Norman  Zimmerman → Norman Zimmerman Strip; 2009-01-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Norman  Zimmerman → Norman Zimmerman; 2009-01-27 to current/open; source msha-controller-operator-history