The BGPRO file must be provided to SMOKE when using county land use data, in order to provide a means of converting county land use to gridded land use. The format for the BGPRO file is the same as for the Area and Mobile spatial surrogate files (see Section 8.4.2, “Area and Mobile Spatial Surrogates Files”). Typically, the same gridded surrogates file would be used, and the Rawbio options would be set to assign the county area, agriculture, or forest surrogates to the various biogenic land use groups.