# Relationship history for MSHA mine 3606126

Current hierarchy: **Robert A  Chess → B & M Coal Company → B & M #2**

- 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 & M Coal Company → B & M #2; 1976-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert A  Chess → B & M #2; 1976-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert A  Chess → B & M Coal Company; 1976-06-01 to current/open; source msha-controller-operator-history