# Relationship history for MSHA mine 1512939

Current hierarchy: **B W  McDonald → Highlands Coal Sales Inc → Tipple #2**

- 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:** Langley Preparation Company Inc → Tipple #2; 1981-06-01 to 1987-01-26; source msha-controller-operator-history
- **controller_controls_mine:** Blevins Kenneth → Tipple #2; 1981-06-01 to 1987-01-26; source msha-controller-operator-history
- **controller_controls_operator:** Blevins Kenneth → Langley Preparation Company Inc; 1981-06-01 to 1987-01-26; source msha-controller-operator-history
- **controller_controls_mine:** CONSOL Energy Inc → Tipple #2; 1986-07-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sierra Coal Company → Tipple #2; 1987-01-27 to 1987-11-24; source msha-controller-operator-history
- **controller_controls_operator:** CONSOL Energy Inc → Sierra Coal Company; 1987-01-27 to 1987-11-24; source msha-controller-operator-history
- **controller_controls_mine:** B W  McDonald → Tipple #2; 1987-05-22 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Highlands Coal Sales Inc → Tipple #2; 1987-11-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** B W  McDonald → Highlands Coal Sales Inc; 1987-11-25 to current/open; source msha-controller-operator-history