# Relationship history for MSHA mine 3200757

Current hierarchy: **Harley  Neshem → Gratech Co Ltd → Gratech Portable #2**

- 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:** Harley  Neshem → Gratech Portable #2; 1997-05-01 to 2020-03-29; source msha-controller-operator-history
- **operator_operates_mine:** Gratech Co Ltd → Gratech Portable #2; 1997-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harley  Neshem → Gratech Co Ltd; 1997-10-01 to 2020-03-29; source msha-controller-operator-history
- **controller_controls_mine:** Harley  Neshem et al → Gratech Portable #2; 2020-03-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harley  Neshem et al → Gratech Co Ltd; 2020-03-30 to current/open; source msha-controller-operator-history