# Relationship history for MSHA mine 4406061

Current hierarchy: **William K  Ison; Charles K  Ison → Ison Coal Company Inc → #1 Prep Plant**

- 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:** Charles K  Ison et al → #1 Prep Plant; 1982-05-06 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ison Coal Company Inc → #1 Prep Plant; 1984-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Charles K  Ison et al → Ison Coal Company Inc; 1984-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William K  Ison et al → Ison Coal Company Inc; 1984-03-01 to current/open; source msha-controller-operator-history