# Relationship history for MSHA mine 1700557

Current hierarchy: **State Of Maine → MaineDOT → Region 4 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

- **controller_controls_mine:** State Of Maine → Region 4 Portable Unit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** State Of Maine → Region 4 Portable Unit; 1981-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M D O T → Region 4 Portable Unit; 1981-07-01 to 2007-04-29; source msha-controller-operator-history
- **controller_controls_operator:** State Of Maine → M D O T; 1981-07-01 to 2007-04-29; source msha-controller-operator-history
- **operator_operates_mine:** MaineDOT → Region 4 Portable Unit; 2007-04-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** State Of Maine → MaineDOT; 2007-04-30 to current/open; source msha-controller-operator-history