No iteration numbers. Suppresses the output of .node and .poly files, so your input files won't be overwritten. (If your input is a .poly file only, a .node file is written.) Cannot be used with the -r switch, because that would overwrite your input .ele file. Shouldn't be used with the -q, -a, -u, or -s switch if you are using a .node file for input, because no .node file is written, so there is no record of any added Steiner points.