I had put in a case to PTC, (Not sure I like the new case logger workflow). I just received a call back from PTC.
I'd always thought this was an error file, because in the past when it was a toolkit application if you had the paths incorrect you'd be notified of that fact.
Turns out this is just a "Trail File" of what FRT is doing. It's not an error file at all.
Seems to me that debug is a bad name for it.