# Relationship history for MSHA mine 3301835

Current hierarchy: **Dolvin Howard → D & M Coal Inc → D & M Clay & Shale Pit**

- 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:** D & M Coal Inc → D & M Clay & Shale Pit; 1971-01-01 to 1972-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Dolvin Howard → D & M Clay & Shale Pit; 1971-01-01 to 1972-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Dolvin Howard → D & M Coal Inc; 1971-01-01 to 1972-12-31; source msha-controller-operator-history
- **operator_operates_mine:** D & M Coal Inc → D & M Clay & Shale Pit; 1973-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dolvin Howard → D & M Clay & Shale Pit; 1973-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dolvin Howard → D & M Coal Inc; 1973-01-01 to current/open; source msha-controller-operator-history