# Relationship history for MSHA mine 3606985

Current hierarchy: **Johnson John & Helvin Krise → J & K Coal Company → No 1 Drift Tunnel**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** J & K Coal Company → No 1 Drift Tunnel; 1980-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Johnson John & Helvin Krise → No 1 Drift Tunnel; 1980-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Johnson John & Helvin Krise → J & K Coal Company; 1980-06-01 to current/open; source msha-controller-operator-history