This attribute controls the appearance of annotated axes by
determining whether labels should be drawn to represent the
numerical values along each axis. It takes a separate value for
each physical axis so that, for instance, the setting "NumLab(2)=1" specifies that numerical labels should be drawn for
the second axis.
If the NumLab value for an axis is non-zero (the default),
then numerical labels will be drawn for that axis, otherwise
they will be omitted.