### Linecolor variable

lc variable tells the program to use the value read from one column of the input data as a linetype index, and use the color belonging to that linetype. This requires a corresponding additional column in the using specifier. Text colors can be set similarly using tc variable.

Examples:

         # Use the third column of data to assign colors to individual points
         plot 'data' using 1:2:3 with points lc variable

         # A single data file may contain multiple sets of data, separated by two
         # blank lines.  Each data set is assigned as index value (see `index`)
         # that can be retrieved via the `using` specifier `column(-2)`.
         # See `pseudocolumns`.  This example uses to value in column -2 to
         # draw each data set in a different line color.
         plot 'data' using 1:2:(column(-2)) with lines lc variable