If P is a segment key whose databyte bit 1 {no-call (p1,nocall)} is zero and whose bits 4:7 are 0 {thus a red segment key} and P designates a node whose slot 15 holds a well formed format key {(p1,redseg)} indicating a segment keeper key {(p1, segkeepslot)} then any jump to P goes to the segment keeper key.

If N is a segment key whose no-call bit {(p1,nocall)} is 1 or to a segment node without a segment keeper key
{(p1,segkeepslot)} then: