The patterns to which numerical values are assigned in deriving the
primary in the extension of the Henry System of fingerprint
classification used by the Federal Bureau of Investigation are the
whorl-type patterns, which occur in about 30 percent of all
The whorl is that type of pattern in which at least two deltas are
present with a recurve in front in each. Figures 191 to 193 reflect
the minimum requirements for the whorl.
It is important to note that the above definition is very general;
however, this pattern may be subdivided for extension purposes in
large groups where whorls are predominant. Even though this extension
may be used, all types of whorls are grouped together under the
general classification of Whorl and are designated by the letter
The aforementioned subdivisions are as follows: The Plain Whorl, The
Central Pocket Loop, The Double Loop, and The Accidental.