# Relationship history for MSHA mine 4202240

Current hierarchy: **Stevens Robert C & Robert E → Keystone Conversions Llc → KEYSTONE 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

- **operator_operates_mine:** Keystone Conversions Llc → KEYSTONE PIT; 1999-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stevens Robert C & Robert E → KEYSTONE PIT; 1999-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stevens Robert C & Robert E → Keystone Conversions Llc; 1999-03-01 to current/open; source msha-controller-operator-history