# Relationship history for MSHA mine 3609534

Current hierarchy: **Frank J  Sokoloski → Heritage Excavating and Stone → EXTEC Screen (SN7085-6993)**

- 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:** Frank J  Sokoloski → EXTEC Screen (SN7085-6993); 2004-11-08 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Heritage Excavating and Stone → EXTEC Screen (SN7085-6993); 2007-06-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frank J  Sokoloski → Heritage Excavating and Stone; 2007-06-18 to current/open; source msha-controller-operator-history