The v.out.ascii GRASS module performs the function of v.in.ascii in reverse, i.e., it converts vector maps in binary format to ASCII format. These two companion programs are useful both for importing and exporting vector maps between GRASS and other software, and for transferring data between machines. The field separator may be a character, the word ‘tab’ (or ‘t’) for tab, ‘space’ (or ‘ ‘) for a blank, or ‘comma’ (or ‘,’) for a comma. An attribute table is only created if it is needed, i.e. when at least one attribute column is present in the input file besides geometry columns. The attribute column will be auto-scanned for type, but may be explicitly declared along with the geometry columns using the columns parameter. Latitude/Longitude data may be given in a number of ways. Decimal degrees must be positive or negative instead of using a hemisphere letter. Mixed coordinates must use a hemisphere letter. Whole minutes and seconds must always contain two digits (example: use 167:03:04.567, and not 167:3:4.567). Acceptable formats: key: D=Degrees, M=Minutes, S=Seconds, h=Hemisphere (N,S,E,W) In special cases of data import, such as the import of large LIDAR datasets (millions of data points), it may be necessary to disable topology support (creating a GRASS vector level 1 vector map) due to memory constraints. This is done with the -b flag. As only very few vector modules support points data processing at vector level 1, usually topology is required (vector level 2). Therefore it is recommended that the user first try to import the data without creating a database (the -t flag) or within a subregion (the -r flag) before resorting to the disabling of topology. A GRASS ASCII vector map (in standard format mode) may contain a mix of primitives including points, lines, boundaries, centroids, areas, faces, and kernels. The GRASS ASCII vector format may contain a header with various metadata (see example below). The header is not required if the -n flag is used. The header is similar as the head file of vector binary format but contains bounding box also. Key words are: Any line starting with the hash character (‘#’) will be treated as a comment and skipped completely if located in the main data file. If located in the header, as defined by the skip parameter, it will be treated as a header line and written to the history file. Source.