# Relationship history for MSHA mine 1508121

Current hierarchy: **Summers R E → Triple E Coal Company → Triple E Coal Strip**

- 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:** Triple E Coal Company → Triple E Coal Strip; 1975-02-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Summers R E → Triple E Coal Strip; 1975-02-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Summers R E → Triple E Coal Company; 1975-02-18 to current/open; source msha-controller-operator-history