# Relationship history for MSHA mine 3400971

Current hierarchy: **Melvin Harry B → P M M Of Oklahoma Inc → P M M Mine #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

- **operator_operates_mine:** P M M Of Oklahoma Inc → P M M Mine #1; 1976-07-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Melvin Harry B → P M M Mine #1; 1976-07-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Melvin Harry B → P M M Of Oklahoma Inc; 1976-07-15 to current/open; source msha-controller-operator-history