# Relationship history for MSHA mine 2103974

Current hierarchy: **Joseph D  Lind → Lind's Sand & Gravel → Portec Screen**

- 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:** Lind's Sand & Gravel → Portec Screen; 2020-05-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Joseph D  Lind → Portec Screen; 2020-05-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Joseph D  Lind → Lind's Sand & Gravel; 2020-05-15 to current/open; source msha-controller-operator-history