Within the whorl group, the subclassification type central pocket
loop is used for extension purposes only. In general classification
it is designated by the letter W. Figures 213 to 236 are central
The central pocket loop type of whorl has two deltas and at least one
ridge making a complete circuit, which may be spiral, oval, circular,
or any variant of a circle. An imaginary line drawn between the two
deltas must not touch or cross any of the recurving ridges within the
inner pattern area. A recurving ridge, however, which has an appendage
connected with it in the line of flow and on the delta side cannot be
construed as a circuit. An appendage connected at that point is
considered to spoil the recurve on that side.
In lieu of a recurve in front of the delta in the inner pattern area,
an obstruction at right angles to the line of flow will suffice.
It is necessary that the inner line of flow be fixed artificially.
The inner line of flow is determined by drawing an imaginary line
between the inner delta and the center of the innermost recurve or
In the central pocket loop, one or more of the simple recurves of the
plain loop type usually recurve a second time to form a pocket within
the loop. The second recurve, however, need not be a continuation
of--or even connected with--the first. It may be an independent ridge.
If no second recurve is present, an obstruction at right angles to the
inner line of flow is acceptable in lieu of it. An obstruction may be
either curved or straight. A dot, of course, may not be considered an
The definition does not require a recurve to cross the line of flow
at right angles. The angle test needs to be applied to obstructions
The recurve or obstruction of the central pocket loop, as that of the
plain whorl, must be free of any appendage connected to it at the
point crossed by the line of flow and on the delta side. An appendage
at that point is considered to spoil the recurve or obstruction.
Figures 237 and 238 are also central pocket loops despite the
appendages connected to the recurves, because they are not connected
at the point crossed by the line of flow.
Figure 239, although possessing a recurve, is classified as a loop
because the second delta is located on the only recurving ridge.
Figures 240 to 244, although possessing one delta and a delta
formation, are classified as loops because the obstructions do not
cross the line of flow at right angles.
Figures 245 to 254 have two deltas and one or more recurves, but they
are classified as loops because each recurve is spoiled by an
appendage connected to it at the point crossed by the line of flow.