# Relationship history for MSHA mine 0504347

Current hierarchy: **Rossmiller Richard H → Enzac Corp → Blackhawk Station**

- 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:** Enzac Corp → Blackhawk Station; 1988-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rossmiller Richard H → Blackhawk Station; 1988-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rossmiller Richard H → Enzac Corp; 1988-05-01 to current/open; source msha-controller-operator-history