# Relationship history for MSHA mine 1901075

Current hierarchy: **Denis J  Dorr → Denis Engineering & Machinery Corp → ROSENFELD HARTFORD AVE. PIT**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Denis J  Dorr → ROSENFELD HARTFORD AVE. PIT; 1996-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Denis Engineering & Machinery Corp → ROSENFELD HARTFORD AVE. PIT; 1999-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Denis J  Dorr → Denis Engineering & Machinery Corp; 1999-07-01 to current/open; source msha-controller-operator-history