The preference field axis.pad controls how much space is added by an axis when the AUTO setting is used for either the lower or upper limit. If is given as a fraction of the data range along the axis; the default is 0.05 which means that if the data covers x=10 to 20 then the padding will be 0.5 for a linear scale and 0.05 * log10(2) for a logarithmic scale.

When explicit limits are given the padding is ignored, which means that in the following the final limits only use the padding for the maximum-displayed value of the X axis (but note how the padding has changed to account for the new X axis "data range" of -10 to 200 rather than 10 to 200):

chips> clear()
chips> add_curve([10,20,50, 200], [1, 2, 5, 10])
chips> get_plot_range()
       [0.5, 209.5, 0.55000000000000004, 10.449999999999999]
chips> limits(X_AXIS, -10, AUTO)
chips> limits(Y_AXIS, 0, 11)
chips> get_plot_range()
       [-10.0, 210.5, 0.0, 11.0]

If you still want the benefits of the AUTO setting - namely automatic rescaling when new data is added - but do not want the extra padding then either change the preference setting or override the current value with:

chips> set_preference("axis.pad", "0")
chips> set_axis(["pad", 0])

The first version will use no padding for any new plots created, but will not change any existing plots, whereas the second value only changes the current plot.