# Relationship history for MSHA mine 0800921

Current hierarchy: **Tanner Anthony → Springs Construction Equipment Company Inc → Tanner Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Springs Construction Equipment Company Inc → Tanner Mine; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tanner Anthony → Tanner Mine; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tanner Anthony → Springs Construction Equipment Company Inc; 1979-01-01 to current/open; source msha-controller-operator-history