# Relationship history for MSHA mine 1515548

Current hierarchy: **Brandenburg Troy → B B W Coal Inc → No1**

- 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:** B B W Coal Inc → No1; 1986-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brandenburg Troy → No1; 1986-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brandenburg Troy → B B W Coal Inc; 1986-03-01 to current/open; source msha-controller-operator-history