# Relationship history for MSHA mine 4607135

Current hierarchy: **Shepperd William B → B & J Contractors → W & B Mines #1 (Surface)**

- 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

- **controller_controls_mine:** Shepperd William B → W & B Mines #1 (Surface); 1986-04-07 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** B & J Contractors → W & B Mines #1 (Surface); 1986-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Shepperd William B → B & J Contractors; 1986-06-01 to current/open; source msha-controller-operator-history