Normally, x11perfcomp uses the first file specified to determine which specific tests it should report on. Some (non-DEC :) servers may fail to perform all tests. In this case, x11perfcomp automatically substitutes in a rate of 0.0 objects/second. Since the first file determines which tests to report on, this file must contain a superset of the tests reported in the other files, else x11perfcomp will fail.
You can provide an explicit list of tests to report on by using the -l switch to specify a file of labels. You can create a label file by using the -label option in x11perf.
16 -r Specifies that the output should also include relative server performance.
16 -ro Specifies that the output should include only relative server performance.
16 -l label_file Specifies a label file to use.
Joel McCormack just munged them together a bit.