In the AMBA® 4 AXI4-Stream Protocol Version: 1.0 Specification it is written that
"If TDATA is not present, it is required that TSTRB is not present."
"In the absence of TDATA and TKEEP, all upsizing and downsizing operations must operate in the same manner as they would for a single data byte."
If TDATA, TKEEP, and TSTRB are not there then how upsizing, downsizing can happen ?
How upsizing and downsizing can happen for single data byte ?
Without TDATA what is significance of this protocol ?