-AS/ignored value, the third octet is reserved and the fourth octet is a prefix length mask, which
-is applied to the source IP before rate-limiting.
+AS/ignored value, the third octet is the maximum number of source IPs tracked (plus one, times 4096)
+and the fourth octet is a prefix length mask, which is applied to the source IP before rate-limiting.
+
+See `collision_prob.py` for collision probabilities in the hash table to estimate the size you
+should use.