"EII"
spherical, equal volume
"VII"
spherical, unequal volume
"EEI"
diagonal, equal volume and shape
"VEI"
diagonal, varying volume, equal shape
"EVI"
diagonal, equal volume, varying shape
"VVI"
diagonal, varying volume and shape
"EEE"
ellipsoidal, equal volume, shape, and orientation
"VEE"
ellipsoidal, equal shape and orientation (*)
"EVE"
ellipsoidal, equal volume and orientation (*)
"VVE"
ellipsoidal, equal orientation (*)
"EEV"
ellipsoidal, equal volume and equal shape
"VEV"
ellipsoidal, equal shape
"EVV"
ellipsoidal, equal volume (*)
"VVV"
ellipsoidal, varying volume, shape, and orientation