# Relationship history for MSHA mine 2600398

Current hierarchy: **Halliburton Company → Imco Services → Pleasant View**

- 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:** Halliburton Company → Pleasant View; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Tom Norris Inc → Pleasant View; 1950-01-01 to 1979-02-05; source msha-controller-operator-history
- **controller_controls_mine:** Thomas D Norris → Pleasant View; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas D Norris → Tom Norris Inc; 1950-01-01 to 1979-02-05; source msha-controller-operator-history
- **operator_operates_mine:** Imco Services → Pleasant View; 1979-02-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Halliburton Company → Imco Services; 1979-02-06 to current/open; source msha-controller-operator-history