The Science of Fingerprints: Classification and Uses

by United States. Federal Bureau of Investigation

(3) Type of small letter (sequence a, t, r).

b. The numerator, by—

(1) Count.

(2) Position.

(3) Type.

Thus

A	precedes	T
A		A

A	precedes	A
rAt		A3t

A	precedes	A
aA		Aa

A	precedes	A
At		Ar