There are two mechanisms for embedding data into a stream of gnuplot commands. If the special filename '-' appears in a plot command, then the lines immediately following the plot command are interpreted as inline data. See special-filenames. Data provided in this way can only be used once, by the plot command it follows.
The second mechanism defines a named data block as a here-document. The named data is persistent and may be referred to by more than one plot command. Example:
$Mydata << EOD 11 22 33 first line of data 44 55 66 second line of data # comments work just as in a data file 77 88 99 EOD stats $Mydata using 1:3 plot $Mydata using 1:3 with points, $Mydata using 1:2 with impulses
Data block names must begin with a $ character, which distinguishes them from other types of persistent variables. The end-of-data delimiter (EOD in the example) may be any sequence of alphanumeric characters.
The storage associated with named data blocks can be released using undefine command. undefine $* frees all named data blocks at once.