# Relationship history for MSHA mine 1600257

Current hierarchy: **Halliburton Company → Halliburton → Halliburton**

- 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:** Baroid Drilling Fluids Inc → Halliburton; 1950-01-01 to 1996-03-04; source msha-controller-operator-history
- **controller_controls_mine:** Nl Industries Inc → Halliburton; 1950-01-01 to 1996-03-04; source msha-controller-operator-history
- **controller_controls_operator:** Nl Industries Inc → Baroid Drilling Fluids Inc; 1950-01-01 to 1996-03-04; source msha-controller-operator-history
- **controller_controls_mine:** Dresser Industries Inc → Halliburton; 1994-01-21 to 1998-02-25; source msha-controller-operator-history
- **operator_operates_mine:** Baroid Drilling Fluids Inc → Halliburton; 1996-03-05 to 1998-02-25; source msha-controller-operator-history
- **controller_controls_operator:** Dresser Industries Inc → Baroid Drilling Fluids Inc; 1996-03-05 to 1998-02-25; source msha-controller-operator-history
- **operator_operates_mine:** Halliburton → Halliburton; 1998-02-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Halliburton Company → Halliburton; 1998-02-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Halliburton Company → Halliburton; 1998-02-26 to current/open; source msha-controller-operator-history