# Relationship history for MSHA mine 2700287

Current hierarchy: **Ivar  Martin → Ivar Martin → PORTABLE UNIT**

- 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:** Ivar Martin → PORTABLE UNIT; 1989-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ivar  Martin → PORTABLE UNIT; 1989-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ivar  Martin → Ivar Martin; 1989-10-01 to current/open; source msha-controller-operator-history