TLAST in AXI4-Stream is used to denote the last transfer of a block of data. TUSER is for ancillary information which qualifies or augments the primary data in TDATA. The Complex Multiplier operates on a per-sample basis where each operation is independent of any before or after. Because of this, there is no need for TLAST on a complex multiplier, nor is there any need for TUSER. The TLAST and TUSER signals are supported on each channel purely as an optional aid to system design for the scenario in which the data stream being passed through the Complex Multiplier does indeed have some packetization or ancillary field, but which is not relevant to the Complex Multiplier. The facility to pass TLAST and/or TUSER removes the burden of matching latency to the TDATA path, which can be variable, through the Complex Multiplier core.