# Relationship history for MSHA mine 1514586

Current hierarchy: **Schweitzer Roy B → R B S Inc → Hard Dollar #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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Schweitzer Roy B → Hard Dollar #2; 1976-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Marcum Thomas Ray → Hard Dollar #2; 1982-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rocky Mountain Coal Company → Hard Dollar #2; 1984-05-01 to 1985-01-06; source msha-controller-operator-history
- **controller_controls_operator:** Marcum Thomas Ray → Rocky Mountain Coal Company; 1984-05-01 to 1985-01-06; source msha-controller-operator-history
- **operator_operates_mine:** R B S Inc → Hard Dollar #2; 1985-01-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schweitzer Roy B → R B S Inc; 1985-01-07 to current/open; source msha-controller-operator-history