The Flood Insurance Rate Map (FIRM) depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event (A or AE) and the 0.2-percent-annual- chance flood event (X). The FIRM data can be derived from Flood Insurance Studies (FISs) and previously published Flood Insurance Rate Maps (FIRMs). The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). This database has been created by digitizing data from georefrenced paper FIRM maps and adding information from FIS where available. All FIRMs were georeferenced at a 1:4000 scale or finer. This data should be used as a reference layer, not as an authoritative source.

The Flood Insurance Rate Map (FIRM) depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event (A or AE) and the 0.2-percent-annual- chance flood event (X). The FIRM data can be derived from Flood Insurance Studies (FISs) and previously published Flood Insurance Rate Maps (FIRMs). The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). This database has been created by digitizing data from georefrenced paper FIRM maps and adding information from FIS where available. All FIRMs were georeferenced at a 1:4000 scale or finer. This data should be used as a reference layer, not as an authoritative source.

Section 11 of FEMA's "Flood Insurance Rate Map (FIRM) Database Technical Reference: Preparing Flood Insurance Rate Map Databases (Nov. 2022)" document contains a detailed description of each attribute code and a reference to other relevant information.

https://www.fema.gov/flood-maps/guidance-reports/guidelines-standards/technical-references-flood-risk-analysis-and-mapping

https://www.fema.gov/sites/default/files/documents/fema_firm-database-technical-reference_112022.pdf