ars in illustration
377. The approximate ridge count is not sufficient to place this print
properly in the large files of the FBI because in certain general
complete classification formulas the accurate ridge count is needed to
obtain an extension. These extensions use a smaller grouping of ridge
counts to form a valuation table, and in this way, differ from the
larger grouping of ridge counts which form the basis of the
subsecondary classification. These extensions are called the second
subsecondary and the special loop extension and are outlined in
chapter VI.

[Illustration: 374. Improper.]

[Illustration: 375. Proper.]

[Illustration: 376. Improper.]

[Illustration: 377. Proper.]

There are two additional points which illustrate the FBI's need for
the delta, ridges, and core to show clearly in loops. The first point
is set forth: the ridge count of the loop may be needed to obtain the
key classification. The key classification is an actual ridge count,
and no valuation table is used to obtain a subdivision. The key
classification is used as an integral part of the fingerprint filing
system. The second point is as follows: the ridge count may be needed
to obtain the final classification. The final classification is an
actual ridge count, and no valuation table is used to obtain a
subdivision. The final classification is used as an integral part of
the fingerprint filing system.

The following are just a few examples to illustrate the completeness
of the classification formula used in the FBI fingerprint file:

12 M 9 R OIO 11

S 1 R IOI

Key Major Primary Secondary Subsecondary Final

6 17 aW IIO 9

1 U OII
Key Primary Small letter Subsecondary Final
Secondary

8 S 1 Ua II 6
S 1 U III

Key Major Primary Small letter (Subsecondary Final
Secondary Extension)

SML (Second
SML Subsecondary)
5 0 5 U IOO 14

I 17 U IOO