# Relationship history for MSHA mine 2902230

Current hierarchy: **Urban  Martinez → Z-4 ENTERPRISES INC → PORTABLE SCREEN #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:** Z-4 ENTERPRISES INC → PORTABLE SCREEN #1; 2001-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Urban  Martinez → PORTABLE SCREEN #1; 2001-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Urban  Martinez → Z-4 ENTERPRISES INC; 2001-11-16 to current/open; source msha-controller-operator-history