# Relationship history for MSHA mine 4002817

Current hierarchy: **Leach Bobby A & David Cofer → B & D Equipment Company → B & D Equipment Co Areas #1&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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** B & D Equipment Company → B & D Equipment Co Areas #1&2; 1982-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Leach Bobby A & David Cofer Et Al → B & D Equipment Co Areas #1&2; 1982-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leach Bobby A & David Cofer Et Al → B & D Equipment Company; 1982-12-01 to current/open; source msha-controller-operator-history