Description: For official parcel records please contact the Sonoma County Assessor (707)565-1888. The GIS parcels have been and are continuing to be orthorectifed or improved to match the best available orthophotography. Improvement of the parcels is as follows; Individual Assessor Parcel pages in CAD dwg format are rectified to the orthophoto. COGO & survey data are used when available and in sufficient quantities to enable the bulk of an Assessor Parcel page to be digitized using said information. Polygons are generated directly from the COGO data, CAD dwg are exported to feature classes, where polygons are then generated. A spatial join is used to attribute the newly generated polygons. Polygons are then assigned an accuracy rank based on source, quality of the fit to the orthophoto, and RMS error encountered during rectification (only the Scanned Assessor map will have and RMS error associated with them, scanned assessor maps are no longer used but had been in the past) See the fields RANK and DESCRIPTION for information on fit assessment.