# Relationship history for MSHA mine 1508013

Current hierarchy: **Swartwood T Marshall → S O Coal Company Inc → No 1 Mine**

- 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:** Ronald Carol Smith Coal Company → No 1 Mine; 1975-01-23 to 1976-01-08; source msha-controller-operator-history
- **controller_controls_mine:** Smith Ronald Carol Coal Company → No 1 Mine; 1975-01-23 to 1976-01-08; source msha-controller-operator-history
- **controller_controls_operator:** Smith Ronald Carol Coal Company → Ronald Carol Smith Coal Company; 1975-01-23 to 1976-01-08; source msha-controller-operator-history
- **operator_operates_mine:** S O Coal Company Inc → No 1 Mine; 1976-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Swartwood T Marshall → No 1 Mine; 1976-01-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Swartwood T Marshall → S O Coal Company Inc; 1976-01-09 to current/open; source msha-controller-operator-history