Water (Loop) type accounts for 60 - 65% (3 main types): has a center and an intersection.

• UL (Ulnar Loop): The direction of the heart flows to the little finger
• RL (Radial Loop): The direction of the heart flows to the thumb
• ULS (Sharp Ulnar): UL ridges are vertical
• UL horizontal: UL ridge is horizontal
• LF (Falling Loop): There can be many pouring directions but only 1 intersection, exception fingerprints in the water group

Source

• Identify & catergorize fingerprints
• Classify fingerprints