Extra lines at the start of a data file may be explicitly ignored using the
skip keyword in the plot command. A single additional line containing text
column headers may be present. It is skipped automatically if the plot command
refers explicitly to column headers, e.g. by using them for titles.
Otherwise you may need to skip it explicitly either by adding one to the skip
count or by setting the attribute set datafile columnheaders.
See skip (p. ), columnhead (p. ), autotitle columnheader (p. ), set datafile (p. ).