code: def decode(self, pdu):
          
          if _debug: BVLCI._debug("decode %s", str(pdu))
  
          # copy the basics
          PCI.update(self, pdu)
  
          self.bvlciType = pdu.get()
          if self.bvlciType != 0x81:
              raise DecodingError("invalid BVLCI type")
  
          self.bvlciFunction = pdu.get()
          self.bvlciLength = pdu.get_short()
  
          if (self.bvlciLength != len(pdu.pduData) + 4):
              raise DecodingError("invalid BVLCI length")
docs: decode the contents of the PDU into the BVLCI.