# Relationship history for MSHA mine 4606233

Current hierarchy: **Perry Milton → Beech Knob Coal Company → Surface No 1 Mine**

- 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:** Beech Knob Coal Company → Surface No 1 Mine; 1980-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Perry Milton → Surface No 1 Mine; 1980-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Perry Milton → Beech Knob Coal Company; 1980-09-01 to current/open; source msha-controller-operator-history