What is the difference between dicomrt2matlab's contours.points and contours.VoxPoints?

What is the difference between dicomrt2matlab 's contours.Points and contours.VoxPoints?

One set appears flipped over the z-axis with different z-values; compare:

scatter3(contours(9).Points(:,1),contours(9).Points(:,2),contours(9).Points(:,3))
scatter3(contours(9).VoxPoints(:,1),contours(9).VoxPoints(:,2),contours(9).VoxPoints(:,3))

I am currently working to answer this question. readRTstructures contains the answer, e.g.:

contours(i).Points = vertcat(segments{:});

    %%Save contour points in voxel coordinates
    contours(i).VoxPoints = xfm \ [contours(i).Points ones(size(contours(i).Points,1), 1)]';
    contours(i).VoxPoints = contours(i).VoxPoints(1:3,:)';

I suppose it involves the DICOM orientation; this webpage appears to be their source for xfm. getAffineXfm writes:

% Based on http://nipy.sourceforge.net/nibabel/dicom/dicom_orientation.html

It appears to me Points stores a representation of the contour surface for MATLAB, whereas VoxPoints is the equivalent for DICOM, according to nipy.org.