# Relationship history for MSHA mine 1515826

Current hierarchy: **Harold K  Simpson → S & B Coal Company Inc → S & B No 1b**

- 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:** Harold K  Simpson → S & B No 1b; 1982-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** S & B Coal Company Inc → S & B No 1b; 1986-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harold K  Simpson → S & B Coal Company Inc; 1986-11-01 to current/open; source msha-controller-operator-history