Plot Process

Many of the plotting functions take a numeric argument generally called the plot process number. Each plot process is a seperate gnuplot program.[*] To identify which gnuplot process a function is referring to, we use the plot process number. If you don't specify a plot process, the default of 0 (zero) is used. Be careful of using many plot processes. On machines without much physical memory, using a lot of plot processes slows things down badly.