Instead of producing a graph, the table terminal prints out the points on
which a graph would be based, i.e., the results of processing the plot or
splot command, in a multicolumn ASCII table of X Y {Z} R values. The
character R takes on one of three values: "i" if the point is in the active
range, "o" if it is out-of-range, or "u" if it is undefined. The data
format is determined by the format of the axis labels (see set format).
For those times when you want the numbers, you can display them on the
screen or save them to a file. This can be useful if you want to generate
contours and then save them for further use, perhaps for plotting with
plot; see set contour for an example. The same method can be used to
save interpolated data (see set samples and set dgrid3d).