I have been seeing the following AIS message (my location is a bit north of
San Francisco), and I can't identify it in the specs I have access to:

!AIVDM,1,1,,A,?03Ovk1GP0?`000,2*33
!AIVDM,1,1,,A,?03Ovk1GP`FP000,2*2A
!AIVDM,1,1,,A,?03Ovk1a08oP000,2*1D
(these were received in this order, with other messages interspersed)

Note that the first character, which should be holding the message-type
identifier, is '?', which is the 6-bit code for 63. Is there a "Type 63"
message?

I am using the SmartRadio SR-162 receiver, and it has been working well. I
am receiving lots of other messgaes from ships and base stations, but this
one has me stumped. I would appreciate any help!

Thanks,
Paul