# Relationship history for MSHA mine 0404539

Current hierarchy: **Marler Sand & Gravel → Marler Sand & Gravel → Marler 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:** Marler Sand & Gravel → Marler Pit; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Marler Sand & Gravel → Marler Pit; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Marler Sand & Gravel → Marler Sand & Gravel; 1981-09-01 to current/open; source msha-controller-operator-history