# Relationship history for MSHA mine 1509342

Current hierarchy: **Frazier Fred M → Imperial Coal Co Inc → No 3 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

- **operator_operates_mine:** Imperial Coal Co Inc → No 3 Mine; 1975-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Frazier Fred M → No 3 Mine; 1975-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frazier Fred M → Imperial Coal Co Inc; 1975-10-01 to current/open; source msha-controller-operator-history