# Relationship history for MSHA mine 3503457

Current hierarchy: **John  Gregor → Rock Products Inc → Portable #2**

- 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:** John  Gregor et al → Portable #2; 1989-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rock Products Inc → Portable #2; 1997-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  Gregor et al → Rock Products Inc; 1997-12-01 to current/open; source msha-controller-operator-history