[Fig. 104]
When the core is located on a spike which touches the inside of the innermost recurving ridge, the recurve is included in the ridge count only when the delta is located below a line drawn at right angles to the spike.
Figures 105 and 106 are examples of this rule.
[Figs. 105-106]
If the delta is located in areas A, the recurving ridge is counted.
If the delta is located in areas B, the recurving ridge is not counted.
Radial and ulnar loops
The terms "radial" and "ulnar" are derived from the radius and ulna bones of the forearm. Loops which flow in the direction of the ulna bone (toward the little finger) are called ulnar loops and those which flow in the direction of the radius bone are called radial loops.