# Relationship history for MSHA mine 3606457

Current hierarchy: **Robert H  McKay; Robert G  Groft Sr → Manor Coal Company → Manor Coal Co**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Manor Coal Company → Manor Coal Co; 1977-06-01 to 1990-01-14; source msha-controller-operator-history
- **controller_controls_mine:** Russell  Schrecengost et al → Manor Coal Co; 1977-06-01 to 1990-01-14; source msha-controller-operator-history
- **controller_controls_operator:** Russell  Schrecengost et al → Manor Coal Company; 1977-06-01 to 1990-01-14; source msha-controller-operator-history
- **operator_operates_mine:** Manor Coal Company → Manor Coal Co; 1990-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert H  McKay et al → Manor Coal Co; 1990-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert H  McKay et al → Manor Coal Company; 1990-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert G  Groft Sr et al → Manor Coal Company; 1990-01-15 to current/open; source msha-controller-operator-history