question about Agilent/HP VNA output

Hi, everyone. I have a question about the Agilent/HP network analyzer output.

There are totally 4 different files for the same measurement:
*.d1 (data), *.f1 (formatted), *.r1 (raw), *.s1 (S-parameter)

But I found that the data in *.s1 are arranged as a matrix, with the magnitude as dB and phase as degree.

The *.f1 data seems the same as *.s1 but arranged as a column, but no phase information.

But what are those for *.d1 and *.r1? Are they in real/image value or else?

Thanks.