https://www.nwcg.gov/publications/pms205/nwcg-glossary-of-wildland-fire-pms-205/national-fire-incident-reporting-system-unit-identifier-243
National Fire Incident Reporting System unit identifier | NWCG
National Fire Incident Reporting System (NFIRS) fire department ID used to uniquely identify a
fire incident reportingnationalsystemunitidentifier