A. TXC is delayed internally before being driven to the RGMII[x]_TXC pin. This internal delay is always enabled.
B. Data and control information is received using both edges of the clocks. RGMII[x]_TD[3:0] carries data bits 3-0 on the rising edge of RGMII[x]_TXC and data bits 7-4 on the falling edge of RGMII[x]_TXC. Similarly, RGMII[x]_TX_CTL carries TXEN on rising edge of RGMII[x]_TXC and TXERR on falling edge of RGMII[x]_TXC.