OKNEIGH applies formal checks to each record in the input NEIGH format file. For instance, occurrences of alphabetic or punctuation characters or inappropriate variable types is noted in the log file okneigh.log . The information in the first three lines of the input NEIGH file is checked against the actual contents of the file and, in the event of discrepancies, corrected values are written in the respective locations in the output NEIGH format file.