A method for quantitative assessments of spatial accuracy and completeness for line data sets is suggested and explored. Data sets of high er accuracy are used for the assessments. The method utilizes only generally available GIS operations. It works by establishing a number of buffers of increasing width around the lines. For each width, the maps are overlaid, and statistics are computed. By plotting the result s in graphs, the usefulness of the method is demonstrated. The method is explored using the Digital Chart of the World (DCW), with the Norwegian mapping authority's national N250 map series as reference data set.