3.24.16.4 set datafile separator
The command ‘set datafile separator "<char>"‘ tells ‘gnuplot‘ that data fields
in subsequent input files are separated by <char> 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 {"<char>" | whitespace}
 | 
Examples:
|  |       # Input file contains tab-separated fields
      set datafile separator "\t"
 | 
|  |       # Input file contains comma-separated values fields
      set datafile separator ","
 |