# Relationship history for MSHA mine 1516718

Current hierarchy: **Howard Toleman → W H D Coal Company → #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

- **operator_operates_mine:** Lead Branch Coal Company Inc → #1; 1989-09-01 to 1989-11-26; source msha-controller-operator-history
- **controller_controls_mine:** Parks William Lee → #1; 1989-09-01 to 1989-11-26; source msha-controller-operator-history
- **controller_controls_operator:** Parks William Lee → Lead Branch Coal Company Inc; 1989-09-01 to 1989-11-26; source msha-controller-operator-history
- **operator_operates_mine:** W H D Coal Company → #1; 1989-11-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Howard Toleman Et Al → #1; 1989-11-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard Toleman Et Al → W H D Coal Company; 1989-11-27 to current/open; source msha-controller-operator-history