# Relationship history for MSHA mine 2402457

Current hierarchy: **Glen T.  Vergeront; Charles R.  Vergeront → Montana Rock Products Inc → Portable #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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Charles R.  Vergeront et al → Portable #1; 1997-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Montana Rock Products Inc → Portable #1; 2006-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Charles R.  Vergeront et al → Montana Rock Products Inc; 2006-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Glen T.  Vergeront et al → Montana Rock Products Inc; 2006-07-06 to current/open; source msha-controller-operator-history