# Relationship history for MSHA mine 3303764

Current hierarchy: **Proco Inc → Proco Inc → Prep Plant 1**

- 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:** Proco Inc → Prep Plant 1; 1979-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Proco Inc → Prep Plant 1; 1979-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Proco Inc → Proco Inc; 1979-06-01 to current/open; source msha-controller-operator-history