f the secondary in the numerator
column if the letter is present in the right hand, and in the
denominator column if in the left hand. When two or more small letters
of the same type occur immediately adjacent to each other, they are
indicated thus:

1 rU-2a 1 aTa-a.
------- and -------
1 tU3a 1 tA2at

The small-letter groups are of vital importance to the classification
system, as they are of relatively infrequent occurrence, constituting
approximately 7 to 10 percent of all patterns. Generally speaking,
since these patterns are of such rare occurrence, their very presence
often enables the classifier to dispense with the usual subsecondary
classification and the major division which in the majority of cases
are used in the larger groups.

THE SUBSECONDARY CLASSIFICATION (GROUPING OF LOOPS AND WHORLS): In
classifying prints it is necessary to subdivide the secondary groups.
This is accomplished by grouping according to the ridge counts of
loops and the ridge tracings of whorls. The first of the groups filed
in order, which it will be necessary to so subdivide, would ordinarily
be the

1 R
---
1 R

group where no small letters appear. The Federal Bureau of
Investigation, however, has found it necessary to extend this division
to many of the small-letter groups which become cumbersome. The
subsecondary is placed on the classification line just to the right of
the secondary. Ridge counts are translated into small and large,
represented by symbols I and O. The whorl tracings are brought up as
I, M, or O denoting inner, meeting or outer ridge tracings of the
whorl types. Only six fingers may be involved in the subsecondary--numbers
2, 3, 4, 7, 8, and 9.

A ridge count of 1 to 9, inclusive, in the index fingers is brought up
into the subsecondary formula as I. A count of 10 or more is brought
up as O. In the middle fingers a count of from 1 to 10, inclusive, is
brought up as I, and 11 or more is O. In the ring fingers a count of
from 1 to 13 is brought up as I, and 14 or more is O. A loop
subsecondary could appear in the classification formula as

OIO.
---
IIO

Analyzing this example of a subsecondary, one will know that in the
index, middle, and ring fingers of the right hand there are counts of
over 9, under 11, and over 13, while in the left hand there are in the
index, middle, and ring fingers, counts of under 10, under 11, over
13, respectively. The subsecondary classification, therefore,