# Relationship history for MSHA mine 1515389

Current hierarchy: **Fields Thomas → Thomas Fields Coal Company → No 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

- **operator_operates_mine:** Thomas Fields Coal Company → No 1 Surface; 1985-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Fields Thomas → No 1 Surface; 1985-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Fields Thomas → Thomas Fields Coal Company; 1985-10-01 to current/open; source msha-controller-operator-history