# Relationship history for MSHA mine 0100515

Current hierarchy: **Drummond Company Inc → Drummond Company, Inc. → Mary Lee # 1 Mine**

- 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:** Drummond Company Inc → Mary Lee # 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Alabama By-Products Corp → Mary Lee # 1 Mine; 1950-01-01 to 1971-08-31; source msha-controller-operator-history
- **controller_controls_mine:** Alabama By-Products Corp → Mary Lee # 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alabama By-Products Corp → Alabama By-Products Corp; 1950-01-01 to 1971-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Drummond Company, Inc. → Mary Lee # 1 Mine; 1971-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Drummond Company Inc → Drummond Company, Inc.; 1971-09-01 to current/open; source msha-controller-operator-history