# Relationship history for MSHA mine 2301648

Current hierarchy: **Asea Brown Boveri Ltd (ABB) → C-E Refractories → Smithey Pit**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Asea Brown Boveri Ltd (ABB) → Smithey Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** C-E Refractories → Smithey Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Asea Brown Boveri Ltd (ABB) → C-E Refractories; 1979-01-01 to current/open; source msha-controller-operator-history