Easy way to do this is setup a laptop or a pc as a sftp server (download freeftpd) and then set this up in CM as a billing server and have the CDR data get dumped to the PC. This way you can get an idea of each field and compare with 4.x formats. I will see if i can find a doc explaining the fields for you.
Sankar
PS: please remember to rate posts!
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus