Question regarding output file format of usrp_rx_cfile.py

Hi,

I was trying to change the script usrp_rx_cfile.py to generate a .dat
file
capturing the I and Q floats/interleaved shorts but I end up only
getting a
binary output file. Can anyone pls help me understand why the output
file is
in binary format? Other scripts which use gr.file_sink generate .dat
output
file

Thanks for any and all help
Meenaktchi