# Relationship history for MSHA mine 3609165

Current hierarchy: **Darrell G  Spencer → Hepburnia Coal Company → Toby 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Darrell G  Spencer et al → Toby Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hepburnia Coal Company → Toby Mine; 2003-08-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Darrell G  Spencer et al → Hepburnia Coal Company; 2003-08-28 to current/open; source msha-controller-operator-history