plot 'datafile' using <xcol>:<ycol>:xticlabels(3) with <plotstyle>
Axis tick labels may be generated for any of the plot axes: x x2 y y2 z. The ticlabels(4#4labelcol5#5) specifiers must come after all of the data coordinate specifiers in the using portion of the command. For each data point which has a valid set of X,Y[,Z] coordinates, the string value given to xticlabels() is added to the list of xtic labels at the same X coordinate as the point it belongs to. xticlabels() may be shortened to xtic() and so on.
Example:
splot "data" using 2:4:6:xtic(1):ytic(3):ztic(6)
In this example the x and y axis tic labels are taken from different columns than the x and y coordinate values. The z axis tics, however, are generated from the z coordinate of the corresponding point.
Example:
plot "data" using 1:2:xtic( $3 > 10. ? "A" : "B" )
This example shows the use of a string-valued function to generate x-axis
tick labels. Each point in the data file generates a tick mark on x labeled
either "A" or "B" depending on the value in column 3.