CARD: handling of sequence numbers

"...The handling of sequence numbers in MN and RA for resending is not
defined. Should MN increase the sequence number on resend? Should AR
identify a CARD request similar to an old one, except for the sequence
number, as a resend and set a new timer for AR-AR resending? How does
AR identify a "new" request from MN from resends of an old one?"

I agree that we need to be more specific here.
In my opinion, the MN should always increase the sequence number also
for resent messages. In case of a huge delay, a MN may resend a packet 
and receive 2 replies. Different sequence numbers allow the MN to
associate each of the 2 replies to a request. Otherwise we need
to specify how the MN should behave what to do when receiving 2
replies with the same sequence number...
To your last point: Is an AR really required to distinguish a
"resent" Request from a "new" one?

marco