# Relationship history for MSHA mine 0100761

Current hierarchy: **Drummond Company Inc → Hallmark Coal Company Inc → Mt Olive**

- 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:** Hallmark Coal Company Inc → Mt Olive; 1950-01-01 to 1976-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Hallmark Fred H → Mt Olive; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hallmark Fred H → Hallmark Coal Company Inc; 1950-01-01 to 1976-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Hallmark Coal Company Inc → Mt Olive; 1976-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Drummond Company Inc → Mt Olive; 1976-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Drummond Company Inc → Hallmark Coal Company Inc; 1976-04-01 to current/open; source msha-controller-operator-history