# Relationship history for MSHA mine 3603259

Current hierarchy: **David W  Pfleegor → Keystone Filler & Manufacturing Company → Keystone Filler 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:** Keystone Filler & Manufacturing Company → Keystone Filler Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** David W  Pfleegor → Keystone Filler Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David W  Pfleegor → Keystone Filler & Manufacturing Company; 1950-01-01 to current/open; source msha-controller-operator-history