# Relationship history for MSHA mine 1511215

Current hierarchy: **Mc Coy Quentine--Michael Frost & Bob Cortes → D & W Coal Company → No 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:** D & W Coal Company → No 1; 1978-04-01 to 1978-08-28; source msha-controller-operator-history
- **controller_controls_mine:** West B P & Harold West → No 1; 1978-04-01 to 1978-08-28; source msha-controller-operator-history
- **controller_controls_operator:** West B P & Harold West → D & W Coal Company; 1978-04-01 to 1978-08-28; source msha-controller-operator-history
- **operator_operates_mine:** D & W Coal Company → No 1; 1978-08-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mc Coy Quentine--Michael Frost & Bob Cortes → No 1; 1978-08-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mc Coy Quentine--Michael Frost & Bob Cortes → D & W Coal Company; 1978-08-29 to current/open; source msha-controller-operator-history