# Relationship history for MSHA mine 4702881

Current hierarchy: **Trapp Lynn → T-Bird Concrete & Supply → T-BIRD CONCRETE & SUPPLY**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Shamrock Concrete & Supply Inc → T-BIRD CONCRETE & SUPPLY; 1988-08-01 to 1994-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Melvin R Neal → T-BIRD CONCRETE & SUPPLY; 1988-08-01 to 1994-06-30; source msha-controller-operator-history
- **controller_controls_operator:** Melvin R Neal → Shamrock Concrete & Supply Inc; 1988-08-01 to 1994-06-30; source msha-controller-operator-history
- **operator_operates_mine:** T-Bird Concrete & Supply → T-BIRD CONCRETE & SUPPLY; 1994-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Trapp Lynn Et Al → T-BIRD CONCRETE & SUPPLY; 1994-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Trapp Lynn Et Al → T-Bird Concrete & Supply; 1994-07-01 to current/open; source msha-controller-operator-history