# Relationship history for MSHA mine 4104835

Current hierarchy: **Walker M.  Schmidt → Schmidt Land Services, Inc. → Atkinson**

- 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:** Schmidt Oilfield Services Venture → Atkinson; 2010-10-04 to 2012-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Walker  Schmidt et al → Atkinson; 2010-10-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Walker  Schmidt et al → Schmidt Oilfield Services Venture; 2010-10-04 to 2012-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Bay Ltd et al → Schmidt Oilfield Services Venture; 2010-10-04 to 2012-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Schmidt Land Services, Inc. → Atkinson; 2012-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Walker M.  Schmidt → Atkinson; 2012-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Walker M.  Schmidt → Schmidt Land Services, Inc.; 2012-05-01 to current/open; source msha-controller-operator-history