# Relationship history for MSHA mine 1102976

Current hierarchy: **Steven R  Nelson → Tri-Con Materials Inc → WALNUT PORTABLE 544E CRUSHER**

- 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

- **controller_controls_mine:** Steven R  Nelson → WALNUT PORTABLE 544E CRUSHER; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Tri-Con Materials Inc → WALNUT PORTABLE 544E CRUSHER; 1995-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steven R  Nelson → Tri-Con Materials Inc; 1995-08-01 to current/open; source msha-controller-operator-history