[Discuss-gnuradio] Mux setting question - 0xF0F0F0F0

Hi,
What does a mux setting of 0xf0f0f0f0 do? Does it convert the data coming from ADC0 to a complex downcoverted signal which can be obtained at DDC0. I want to know if the I and Q channel both have the inphase and quadrature part or is it just that the I is the digitized data from ADC0 and the Q is just zeros.

Thanks,
John