DAQ2 ZC706 Reference Design axi_ad9144_jesd output data format

What is the data format for tx_data_tdata[127:0]?

Perhaps it is tx_data_tdata[127:0]={DAC3,DAC2,DAC1,DAC0,DAC3,DAC2,DAC1,DAC0} ?

It doesn't appear to be tx_data_tdata[127:0]={DAC1,DAC0,DAC1,DAC0,DAC1,DAC0,DAC1,DAC0} 

What is the device_clk? 500Mhz?