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