# Relationship history for MSHA mine 3610182

Current hierarchy: **William G  Tomko → W. G. Tomko Inc. Contractors → W. G. Tomko 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** W. G. Tomko Inc. Contractors → W. G. Tomko Inc.; 2016-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** William G  Tomko → W. G. Tomko Inc.; 2016-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William G  Tomko → W. G. Tomko Inc. Contractors; 2016-04-19 to current/open; source msha-controller-operator-history