# Relationship history for MSHA mine 4608461

Current hierarchy: **Robertson David → Deep Ford Mining Company Inc → Hm No 1**

- 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:** Deep Ford Mining Company Inc → Hm No 1; 1994-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robertson David → Hm No 1; 1994-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robertson David → Deep Ford Mining Company Inc; 1994-12-01 to current/open; source msha-controller-operator-history