# Relationship history for MSHA mine 4105560

Current hierarchy: **Kent  Strain; Whit  Strain; Ross  Strain → J H Strain and Sons Inc. → Aztec 4250**

- 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

- **controller_controls_mine:** Ernest  Strain et al → Aztec 4250; 1979-10-01 to 2024-09-19; source msha-controller-operator-history
- **operator_operates_mine:** J H Strain and Sons Inc. → Aztec 4250; 2021-04-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ernest  Strain et al → J H Strain and Sons Inc.; 2021-04-05 to 2024-09-19; source msha-controller-operator-history
- **controller_controls_mine:** Kent  Strain et al → Aztec 4250; 2024-09-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kent  Strain et al → J H Strain and Sons Inc.; 2024-09-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Whit  Strain et al → J H Strain and Sons Inc.; 2024-09-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ross  Strain et al → J H Strain and Sons Inc.; 2024-09-20 to current/open; source msha-controller-operator-history