The report documents the development of the Flexible Regional Emissions Data System (FREDS) for the 1980 NAPAP Emissions Inventory. FREDS extracts emissions data, pertinent modeling parameters (e.g., stack height, exhaust gas temperature), and source identification information and applies appropriate temporal, spatial, and pollutant species allocation factors to derive a gridded, speciated, and temporally resolved emissions file suitable as input to regional-scale atmospheric simulation models (e.g., Regional Acid Deposition Model, Regional Oxidant Model). FREDS consists of five main modules (i.e., Model Data Extraction Module, Temporal Allocation Module, Speciation Module, Spatial Allocation Module, and Model Input Preprocessor) which are used to apply allocation factors to the annual emissions data, plus peripheral software used to ensure the quality of (and maintain) the allocation factor files.