"Transducer Up" should be the orientation of the receiver/transceiver if it is at depth, or the orientation of the transmitter/transponder if it is at depth.
"S" package Mk II transmitter, Mk II receiver, or Mk III transceiver in "transducer up" orientation
"P" package Mk II transmitter, Mk II receiver, or Mk III transceiver in "transducer up" orientation
