def decode(self, pdu):
        """decode the contents of the PDU into the BSLCI."""
        if _debug: BSLCI._debug("decode %r", pdu)

        # copy the basics
        PCI.update(self, pdu)

        self.bslciType = pdu.get()
        if self.bslciType != 0x83:
            raise DecodingError("invalid BSLCI type")

        self.bslciFunction = pdu.get()
        self.bslciLength = pdu.get_short()

        if (self.bslciLength != len(pdu.pduData) + 4):
            raise DecodingError("invalid BSLCI length")
decode the contents of the PDU into the BSLCI.