I think some of you voxel guys might find use for this :

http://www.eclipsemods.com/flyby/NORMALS/TS_style_spatial_diagram.png

and the corresponding normal indexes as found in Will's Voxel Editor :

http://www.eclipsemods.com/flyby/NORMALS/wills_editor.jpg

if you need the reference list :

http://www.eclipsemods.com/flyby/NORMALS/flyby1_2.ts.normals