# Relationship history for MSHA mine 1901326

Current hierarchy: **woburn public works → woburn public works → Rifle Range**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** woburn public works → Rifle Range; 2025-07-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** woburn public works → Rifle Range; 2025-07-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** woburn public works → woburn public works; 2025-07-24 to current/open; source msha-controller-operator-history