Interpretation
Before pattern definition can be understood, it is necessary to understand the meaning of a few technical terms used in fingerprint work.
The pattern area is the only part of the finger impression with which we are concerned in regard to interpretation and classification. It is present in all patterns, of course, but in many arches and tented arches it is impossible to define. This is not important, however, as the only patterns in which we need to define the pattern area for classification purposes are loops and whorls. In these two pattern types the pattern area may be defined as follows:
The pattern area is that part of a loop or whorl in which appear the cores, deltas, and ridges with which we are concerned in classifying.
The pattern areas of loops and whorls are enclosed by type lines.
Type lines may be defined as the two innermost ridges which start parallel, diverge, and surround or tend to surround the pattern area.
Figure 11 is a typical loop. Lines A and B, which have been emphasized in this sketch, are the type lines, starting parallel, diverging at the line C and surrounding the pattern area, which is emphasized in figure 12 by eliminating all the ridges within the pattern area.
[Figs. 11-12]
Figures [72 through 101] should be studied for the location of type lines.