The command set datafile separator tells gnuplot that data fields in
subsequent input files are separated by a specific character rather than by
whitespace. The most common use is to read in csv (comma-separated value)
files written by spreadsheet or database programs. By default data fields
are separated by whitespace.
Syntax:
set datafile separator {whitespace | tab | comma | "<chars>"}
Examples:
# Input file contains tab-separated fields
set datafile separator "\t"
# Input file contains comma-separated values fields
set datafile separator comma
# Input file contains fields separated by either * or |
set datafile separator "*|"