# Relationship history for MSHA mine 2700280

Current hierarchy: **Brown John A → John A Brown Excavating → 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** John A Brown Excavating → Portable #1; 1988-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brown John A → Portable #1; 1988-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brown John A → John A Brown Excavating; 1988-10-01 to current/open; source msha-controller-operator-history