# Relationship history for MSHA mine 1518908

Current hierarchy: **Robert L  Clear → Robert Clear Coal Corporation → Straight Creek #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:** Robert L  Clear → Straight Creek #1; 1987-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Charles  Collins → Straight Creek #1; 1992-02-05 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** National Coal Corporation → Straight Creek #1; 2003-05-27 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Calvary Coal Co Inc → Straight Creek #1; 2005-08-01 to 2005-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Charles  Collins → Calvary Coal Co Inc; 2005-08-01 to 2005-11-13; source msha-controller-operator-history
- **operator_operates_mine:** National Coal Corporation → Straight Creek #1; 2005-11-14 to 2006-03-26; source msha-controller-operator-history
- **controller_controls_operator:** National Coal Corporation → National Coal Corporation; 2005-11-14 to 2006-03-26; source msha-controller-operator-history
- **operator_operates_mine:** Robert Clear Coal Corporation → Straight Creek #1; 2006-03-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert L  Clear → Robert Clear Coal Corporation; 2006-03-27 to current/open; source msha-controller-operator-history