# Relationship history for MSHA mine 0203203

Current hierarchy: **Sylvia  Waltemath → A B C Sand & Rock Co Inc → Plant #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

- **controller_controls_mine:** David  Waltemath → Plant #2; 1987-02-01 to 2023-09-15; source msha-controller-operator-history
- **operator_operates_mine:** A B C Sand & Rock Co Inc → Plant #2; 2007-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David  Waltemath → A B C Sand & Rock Co Inc; 2007-12-01 to 2023-09-15; source msha-controller-operator-history
- **controller_controls_mine:** Sylvia  Waltemath → Plant #2; 2023-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sylvia  Waltemath → A B C Sand & Rock Co Inc; 2023-09-16 to current/open; source msha-controller-operator-history