# Relationship history for MSHA mine 0405254

Current hierarchy: **Eric R  Ladd → Roy E Ladd Inc → PORTABLE PLANT A-33.1**

- 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:** Eric R  Ladd et al → PORTABLE PLANT A-33.1; 1991-12-16 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Roy E Ladd Inc → PORTABLE PLANT A-33.1; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Eric R  Ladd et al → Roy E Ladd Inc; 1994-10-01 to current/open; source msha-controller-operator-history