| (1R-U) |
| (1R-U), |
the following special loop extension may be used, utilizing the ridge counts in fingers Nos. 2, 3, 4, 7, 8, 9, and, if necessary, No. 10:
| Ridge Counts | Value |
| 1 to 4, inclusive | 1 |
| 5 to 8, inclusive | 2 |
| 9 to 12, inclusive | 3 |
| 13 to 16, inclusive | 4 |
| 17 to 20, inclusive | 5 |
| 21 to 24, inclusive | 6 |
| 25 and over | 7 |
The resulting values in this extension are brought up into the classification formula directly above the subsecondary in their respective positions, the right hand being the numerator, the left hand being the denominator.
In addition to the extensions already mentioned, fingerprint groups may be divided into male and female, and by age (either by year or by arbitrarily setting an age limit, beyond which a print bearing such an age would be filed separately in a "Reference" or a "Presumptive Dead" file).
In the files of the Federal Bureau of Investigation, all prints bearing an age of 55 through 74 are filed in the "Reference" group and all prints bearing an age of 75 years or more are filed in the "Presumptive Dead" file. Persons 75 years of age or older, in regard to crime, may be considered as generally inactive and thus are filed as "Presumptive Dead." Such a group provides for removing from the other files the cards concerning those of whom no notice is ever received as to death.
A separate file should be maintained for deceased persons, for possible future reference.
A separate file should be maintained for all prints bearing amputations and which have an unequivocal statement or marking from the contributor to that effect.
Permanent scars also may be utilized for this purpose, giving three more groupings: those prints having permanent scars in the right hand, those having a scar in the left, and those in which scars appear in both hands. A separate file may be maintained for mutilated prints whether or not the permanent-scar division is used. This is usually composed of prints so badly mutilated, or so mutilated about the cores and deltas, that intentional mutilation is suspected.