# Relationship history for MSHA mine 1700634

Current hierarchy: **Thelma M  Lancaster → Thelma Lancaster Contractor → COLEMAN PORTABLE SCREEN**

- 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:** Thelma Lancaster Contractor → COLEMAN PORTABLE SCREEN; 1996-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thelma M  Lancaster → COLEMAN PORTABLE SCREEN; 1996-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thelma M  Lancaster → Thelma Lancaster Contractor; 1996-07-01 to current/open; source msha-controller-operator-history