# Relationship history for MSHA mine 0900997

Current hierarchy: **Quality Sands Inc → Quality Sands Inc → Quality Pit**

- 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:** Quality Sands Inc → Quality Pit; 1987-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Quality Sands Inc → Quality Pit; 1987-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Quality Sands Inc → Quality Sands Inc; 1987-03-01 to current/open; source msha-controller-operator-history