# Relationship history for MSHA mine 0504778

Current hierarchy: **State Of Colorado → The State of Colorado DOC Heavy Equipment Tech → Portable #1**

- 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:** State of Colorado DOC Heavy Equipment Tech → Portable #1; 2004-01-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** State Of Colorado → Portable #1; 2004-01-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** State Of Colorado → State of Colorado DOC Heavy Equipment Tech; 2004-01-06 to current/open; source msha-controller-operator-history