# Relationship history for MSHA mine 2901723

Current hierarchy: **Koppen Eckhardt M → Koppen Mining Construction Corp → Spencer Shaft Section 6 7 And 8**

- 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:** Koppen Eckhardt M → Spencer Shaft Section 6 7 And 8; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Koppen Mining Construction Corp → Spencer Shaft Section 6 7 And 8; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Koppen Eckhardt M → Koppen Mining Construction Corp; 1978-03-09 to current/open; source msha-controller-operator-history