This attribute controls the appearance of an annotated
coordinate grid (drawn with the astGridastGrid function) by determining
whether the descriptive labels drawn for each axis of a PlotPlot
should include a description of the units being used on the
axis. It takes a separate value for each physical axis of a
Plot so that, for instance, the setting "LabelUnits(2)=1"
specifies that a unit description should be included in the
label for the second axis.
If the LabelUnits value of a Plot axis is non-zero, a unit
description will be included in the descriptive label for that
axis, otherwise it will be omitted. The default behaviour is to
include a unit description unless the current FrameFrame of the Plot
is a SkyFrameSkyFrame representing equatorial, ecliptic, galactic or
supergalactic coordinates, in which case it is omitted.