# Relationship history for MSHA mine 0503199

Current hierarchy: **Rogers Construction Inc → Schmidt-Tiago Construction Company → Elmer Mack Pit**

- 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:** Walter R  Schmidt → Elmer Mack Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Schmidt-Tiago Construction Company → Elmer Mack Pit; 1978-03-09 to 1980-07-18; source msha-controller-operator-history
- **controller_controls_operator:** Walter R  Schmidt → Schmidt-Tiago Construction Company; 1978-03-09 to 1980-07-18; source msha-controller-operator-history
- **operator_operates_mine:** Schmidt-Tiago Construction Company → Elmer Mack Pit; 1980-07-19 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rogers Construction Inc → Elmer Mack Pit; 1980-07-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rogers Construction Inc → Schmidt-Tiago Construction Company; 1980-07-19 to current/open; source msha-controller-operator-history