# Relationship history for MSHA mine 4201924

Current hierarchy: **Davidson Howard → Dav-Tex Corp → Cisco #1**

- 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:** Davidson Howard → Cisco #1; 1982-06-23 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dav-Tex Corp → Cisco #1; 1985-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Davidson Howard → Dav-Tex Corp; 1985-03-01 to current/open; source msha-controller-operator-history