# Relationship history for MSHA mine 4000811

Current hierarchy: **John B  Herbert → SANGRAVL COMPANY, INC. → SANGRAVL COMPANY, INC.**

- 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:** Sangravl Company Inc → SANGRAVL COMPANY, INC.; 1950-01-01 to 1983-08-01; source msha-controller-operator-history
- **controller_controls_mine:** James A  Skinner → SANGRAVL COMPANY, INC.; 1950-01-01 to 1983-08-01; source msha-controller-operator-history
- **controller_controls_operator:** James A  Skinner → Sangravl Company Inc; 1950-01-01 to 1983-08-01; source msha-controller-operator-history
- **operator_operates_mine:** SANGRAVL COMPANY, INC. → SANGRAVL COMPANY, INC.; 1983-08-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John B  Herbert → SANGRAVL COMPANY, INC.; 1983-08-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John B  Herbert → SANGRAVL COMPANY, INC.; 1983-08-02 to current/open; source msha-controller-operator-history