set (x|y)[<axisnumber>]ticdir (inward|outward|both)
The ‘xticdir’ setting can be used to set whether the ticks along the -axis of a plot point inwards, towards the graph, as by default, or outwards, towards the numeric labels along the axis. They can also be set to point in both directions simultaneously. The syntax for this is as follows:
set xticdir inward set xticdir outward set xticdir both
The same setting can also be made on higher numbered axes, by inserting their numbers after the ‘x’, for example:
set x10ticdir outward
Similarly, the ‘x’ can be substituted with a ‘y’ to set the directions of ticks on vertical axes:
set yticdir inward set y10ticdir both