Before
Add() targets C, the head of category 1
A
47 / 128
B
128 / 128
C
127 / 128
head
D
128 / 128
tail
E
61 / 128
128th element added — C is full, re-linked at tail of category 1
After
A
47 / 128
B
128 / 128
D
128 / 128
C
128 / 128
tail (moved)
E
61 / 128
Next insertion allocates a fresh cluster at the head of category 1