TICKSIZE SMALLX BIGX SMALLY BIGY.

Determine tick intervals for BOX. SMALLX refers to the interval
between small tick marks on the x axis, BIGX refers to the x-axis
interval between large ticks and so forth. If BIG is 0, the axis
routine will supply its own intervals according to the label limits.
If SMALL < 0, the axis will have logarithmic tick spacing and BOX
assumes that the limits are logarithms, e.g. -2 and 2 refers to limits
of 0.01 and 100. If both BIG and SMALL are 0, you'll get SM's default
behaviour.

Negative values of SMALL and BIG are interpreted as specifying the
tickspacing in the decade 1:10, and are scaled to fit the decades
actually plotted. For instance, if you say
   LIMITS 0 1 3 4
   TICKSIZE -1 10 -0.1 1 BOX
then the x-axis will have small ticks at 2, 3, ..., 9 and big ticks at
1 and 10, while the y axis will have small ticks at 1100, 1200, 1300, ...
and big ticks at 1000, 2000, 3000, ... (You might want to use NOTATION
to stop SM using exponential notation for the 10000 label). The most
usual TICKSIZE is probably -1 10, and this may be written -1 0 for
backwards compatibility.

Occasionally you may want to use the same tickspacing in all decades
of your plot. To do this make BIG negative also:
   LIMITS 1.9 2.1 0 1
   TICKSIZE -0.1 -1 0 0 BOX
this is a good way to make an axis very crowded! 

If you really cannot use TICKSIZE to accomplish your needs, you can use
AXIS and provide vectors specifying the positions of the big and little
ticks, and even the axis labels.