# Relationship history for MSHA mine 0203504

Current hierarchy: **John L Dixon; Carol A Ptak → Dixon Rock and Materials LLC → Dixon Rock and Materials LLC**

- 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:** Dixon Rock and Materials LLC → Dixon Rock and Materials LLC; 2024-03-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John L Dixon et al → Dixon Rock and Materials LLC; 2024-03-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John L Dixon et al → Dixon Rock and Materials LLC; 2024-03-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carol A Ptak et al → Dixon Rock and Materials LLC; 2024-03-26 to current/open; source msha-controller-operator-history