# Relationship history for MSHA mine 0600650

Current hierarchy: **Kenneth W  Kovacs → East Coast Sand & Gravel Inc → POWER SCREEN**

- 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:** East Coast Sand & Gravel Inc → POWER SCREEN; 1996-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kenneth W  Kovacs → POWER SCREEN; 1996-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kenneth W  Kovacs → East Coast Sand & Gravel Inc; 1996-04-01 to current/open; source msha-controller-operator-history