The set xdtics commands converts the x-axis tic marks to days of the week
where 0=Sun and 6=Sat. Overflows are converted modulo 7 to dates. set
noxdtics returns the labels to their default values. Similar commands do
the same things for the other axes.
Syntax:
set xdtics
set ydtics
set zdtics
set x2dtics
set y2dtics
set noxdtics
etc.
show xdtics
etc.
See also the set format command.