# Relationship history for MSHA mine 4605636

Current hierarchy: **Smith David F → Smith Construction → Smith No 1 Surface**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Smith Construction → Smith No 1 Surface; 1977-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Smith David F → Smith No 1 Surface; 1977-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Smith David F → Smith Construction; 1977-10-01 to current/open; source msha-controller-operator-history