# Relationship history for MSHA mine 3690001

Current hierarchy: **Vernon E Zerby → Calvin V Lenig Coal Prep & Sales Inc → Lenig Prep Plant**

- 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:** Calvin V Lenig Coal Prep & Sales Inc → Lenig Prep Plant; 1977-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Diann S  (Lenig) Ferry → Lenig Prep Plant; 1977-01-01 to 2005-03-07; source msha-controller-operator-history
- **controller_controls_operator:** Diann S  (Lenig) Ferry → Calvin V Lenig Coal Prep & Sales Inc; 1977-01-01 to 2005-03-07; source msha-controller-operator-history
- **controller_controls_mine:** Vernon E Zerby → Lenig Prep Plant; 2005-03-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vernon E Zerby → Calvin V Lenig Coal Prep & Sales Inc; 2005-03-08 to current/open; source msha-controller-operator-history