# Relationship history for MSHA mine 3101717

Current hierarchy: **Hanson PLC → Nello L Teer Company → Preventive Maintenance Shop**

- 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:** Nello L Teer Company → Preventive Maintenance Shop; 1950-01-01 to 1980-04-14; source msha-controller-operator-history
- **controller_controls_mine:** Nello L  Teer Jr et al → Preventive Maintenance Shop; 1950-01-01 to 1980-04-14; source msha-controller-operator-history
- **controller_controls_operator:** Nello L  Teer Jr et al → Nello L Teer Company; 1950-01-01 to 1980-04-14; source msha-controller-operator-history
- **operator_operates_mine:** Nello L Teer Company → Preventive Maintenance Shop; 1980-04-15 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Company Inc → Preventive Maintenance Shop; 1980-04-15 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → Nello L Teer Company; 1980-04-15 to 1988-11-13; source msha-controller-operator-history
- **operator_operates_mine:** Nello L Teer Company → Preventive Maintenance Shop; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Preventive Maintenance Shop; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Nello L Teer Company; 1988-11-14 to current/open; source msha-controller-operator-history