The parameters used to generate each Aurora 64B/66B core determine the interfaces available for that specific core. USER_DATA_S_AXIS_TX is an interface and the s_axi_tx_* ports are grouped into that interface. The interfaces are visible in the IP symbol as seen in This Figure . One can see the ports grouped in it. In this section, in general, the interface appears as a single row entry followed by the ports which are grouped in an interface by clicking on the + sign beside the interface. Aurora 64B/66B cores can have four to eight interfaces. This Figure shows the Aurora 64B/66B IP symbol for the default core configuration with all flow control options and CRC enabled.