The Secondary is composed of the pattern types present in the index fingers (2 and 7).
The number two finger is used as the numerator and the number seven finger is used as the denominator.
The Secondary is brought up to the classification line to the right of the primary.
Small Letter Group
Prints with an arch (a), tented arch (t) or radial loop (r) in any finger except the index fingers constitute the Small Letter Group of the secondary classification. Small letters consist of a, t, and r only.
Small letters are brought up to the classification in their respective relative positions to the index finger (2 and 7) when appearing in fingers 1, 3, 4, 5, 6, 8, 9, 10.
All small letters must be indicated in the classification formula.
Dashes are used in the classification formula to indicate an ulnar loop or a whorl intervening between the index finger and the first small letter, or between two small letters.
When 2 or more small letter patterns of the same type appears together, they are indicated as: 2a, 3a, 2t, 3t, 2r, or 3r.