# Relationship history for MSHA mine 1800139

Current hierarchy: **Burrell Brothers Coal Corp → Burrell Brothers Coal Corp → Cal #1 Ug**

- 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:** Burrell Brothers Coal Corp → Cal #1 Ug; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Burrell Brothers Coal Corp → Cal #1 Ug; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burrell Brothers Coal Corp → Burrell Brothers Coal Corp; 1950-01-01 to current/open; source msha-controller-operator-history