The report documents the Flexible Regional Emissions Data System (FREDS) for the 1985 NAPAP Emissions Inventory. FREDS extracts emissions data, modeling parameters (e.g., stack height, exhaust gas temperature), and source identification information from point/area source NEDS data, and applies temporal, spatial, and pollutant species allocation factors to derive a gridded, speciated, and temporally resolved emissions file for input to regional scale atmospheric simulation models (e.g., the Regional Acid Deposition Model and Regional Oxidant Model). FREDS consists of seven modules that reformat the data, apply allocation factors to the annual emissions data, and ensure the quality of FREDS output. In addition to FREDS, peripheral software is used to maintain the allocation factor files. Separate programs are used to process point/area sources. The seven modules are the Hydrocarbon Preprocessor, the Quality Control Module, the Model Data Extraction Module, the Temporal Allocation Module, the Speciation Module, the Spatial Allocation Module, and the Model Input Preprocessor. Many of the modules can be implemented in a logical sequence or independently of the others in most cases. For maximum flexibility, FREDS allows the user to define and assign emissions of up to 15 pollutants prior to speciation, the temporal scenario, and other variables.