# Relationship history for MSHA mine 3601256

Current hierarchy: **Vollmer David L → L B Vollmer → Vollmer Strip**

- 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:** L B Vollmer → Vollmer Strip; 1950-01-01 to 1989-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Vollmer L B → Vollmer Strip; 1950-01-01 to 1989-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Vollmer L B → L B Vollmer; 1950-01-01 to 1989-04-30; source msha-controller-operator-history
- **operator_operates_mine:** L B Vollmer → Vollmer Strip; 1989-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vollmer David L → Vollmer Strip; 1989-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vollmer David L → L B Vollmer; 1989-05-01 to current/open; source msha-controller-operator-history