What's the binary format used inside an AUP?

Anyone who's ever opened an AUP file (it's a zip file) sees there's a bunch of ARC files inside.

How does one read these files?  I'm trying to figure out how ArcSight is parsing certain syslog events of mine, so that I can make changes if necessary by overriding the default assigned parser.  I'm trying to read the following



Any ideas?