# Relationship history for MSHA mine 1102875

Current hierarchy: **Porter Bill D → Bill Porter → Porter Portable #2**

- 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:** Porter Bill D → Porter Portable #2; 1986-06-30 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Bill Porter → Porter Portable #2; 1988-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Porter Bill D → Bill Porter; 1988-08-01 to current/open; source msha-controller-operator-history