# Relationship history for MSHA mine 1001961

Current hierarchy: **Donald J  Nelson → Nelson Construction Company → PORTABLE PLANT #3**

- 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:** Donald J  Nelson → PORTABLE PLANT #3; 1986-02-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nelson Construction Company → PORTABLE PLANT #3; 1999-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald J  Nelson → Nelson Construction Company; 1999-08-01 to current/open; source msha-controller-operator-history