The hypothesized similarity of a pair of color systems is proportional to the number of cells of the unique hue point matrix that are the same.
For example, a stage II system differs from a stage IIIgbk in one cell (yellow is split from red in a stage IIIgbk system, but not in a stage II system), so 14 of the 15 off-diagonal cells are the same.

II	W	1
	R	0	1
	Y	0	1	1
	G	0	0	0	1
	B	0	0	0	1	1
	K	0	0	0	1	1	1
		W	R	Y	G	B	K

IIIgbk	W	1
	R	0	1
	Y	0	0	1
	G	0	0	0	1
	B	0	0	0	1	1
	K	0	0	0	1	1	1
		W	R	Y	G	B	K

IIIgb	W	1
	R	0	1
	Y	0	1	1
	G	0	0	0	1
	B	0	0	0	1	1
	K	0	0	0	0	0	1
		W	R	Y	G	B	K

IIIygb	W	1
	R	0	1
	Y	0	0	1
	G	0	0	1	1
	B	0	0	1	1	1
	K	0	0	0	0	0	1
		W	R	Y	G	B	K

IVbk	W	1
	R	0	1
	Y	0	0	1
	G	0	0	0	1
	B	0	0	0	0	1
	K	0	0	0	0	1	1
		W	R	Y	G	B	K

IVgb	W	1
	R	0	1
	Y	0	0	1
	G	0	0	0	1
	B	0	0	0	1	1
	K	0	0	0	0	0	1
		W	R	Y	G	B	K

IVyg	W	1
	R	0	1
	Y	0	0	1
	G	0	0	1	1
	B	0	0	0	0	1
	K	0	0	0	0	0	1
		W	R	Y	G	B	K

V	W	1
	R	0	1
	Y	0	0	1
	G	0	0	0	1
	B	0	0	0	0	1
	K	0	0	0	0	0	1
		W	R	Y	G	B	K