READ /PLANES
[CLEAN\]READ Buffer File /PLANES Min Max
Read only the last axis "planes" between the First and Last implied by Min
and Max. For an LMV-ordered cube, this would be equivalent to
READ Buffer File /RANGE Min Max CHANNEL
However, for transposed data cubes, VML or LVM-ordered for example, this is
not true at all when a Frequency/Velocity axis is present: /RANGE would
specify a subset of this(yet) axis, while /PLANES always indicate a subset
of the 3rd axis of the cube.
Min and Max indicate offsets from Plane 1 and the number of planes Nplane.
Thus Max can be negative: it then indicates Last = Nplane-Max. Also Min=0
and Max=0 implies loading all the channels.