# Relationship history for MSHA mine 1515770

Current hierarchy: **Grant Patrick → Wood Heat Products → Surface**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Grant Patrick → Surface; 1983-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Wood Heat Products → Surface; 1986-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grant Patrick → Wood Heat Products; 1986-10-01 to current/open; source msha-controller-operator-history