# Relationship history for MSHA mine 3606806

Current hierarchy: **Plisko Frank W → Electro-Met Coal Company Inc → Sporio Mine**

- 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

- **controller_controls_mine:** Plisko Frank W → Sporio Mine; 1977-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Electro-Met Coal Company Inc → Sporio Mine; 1979-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Plisko Frank W → Electro-Met Coal Company Inc; 1979-03-01 to current/open; source msha-controller-operator-history