All frames appear to be a multiple of 4 bytes in length.

SD - Sequenced Data

     Last word contains control info
     High order byte
       8-7  PL
       6-5  Rsd
       4-1  PDU Type
     3 Low order bytes
       N(S) (sequence number)

POLL
      Word 1
        Bytes 2-4  N(PS)     Poll seq #
      Word 2
        Byte  1  PDU_TYPE    0x0a = poll
        Bytes 2-4  N(S)      Seq # of last packet sent

STAT
      Word 1
         List element 1 (a SD PDU N(S))
         List element 2 ...

         Resvd      N(PS) PS # to which this is a response
         Resvd      N(MR) maximum # willing to receive now
         PDU_TYPE   N(R)  # of last packet received correctly
         0x0b = STAT