Table I.

The definitions of the six TYPEs and the histological structure each TYPE represents within the white matter (WM).

TYPE	DEFINITION				HISTOLOGICAL STRUCTURE REPRESENTED
	f1	f2	f3	Dieff (i=1,2,3)
I	≠0	=0	=0	[Dg, DL]	unidirectional bundles
II	≠0	≠0	=0	[Dg, DL]	two bundles crossing orthogonally
III	≠0	≠0	≠0	[Dg, DL]	three bundles crossing orthogonally
IV	f1 + f2 + f3 >1			[Dg, DL]	the reference bundles do not fit
V				[DL, ∞)	the WM contaminated by CSF partially
VI				(0, Dg]	experimental noise