Section 3.2.8: The text says:
... Note that an
implementation MAY discard incoming address advertisements - for
example, to avoid the required mapping state, or because advertised
addresses are of no use to it (for example, IPv6 addresses when it
has IPv4 only). Therefore, a host MUST treat address advertisements
as soft state, and the sender MAY choose to refresh advertisements
periodically.
The nesting of examples makes this paragraph very difficult. First,
please separate the MUST statement and the MAY statement. Then, offer
examples to explain the reasons an implementation might choose to
discard incoming address advertisements or refresh advertisements
periodically.
Addresses ART review comment: