significance of out.log?

In a task that completed successfully in FireCloud, I find a file called "out.log".
It seems to be a table of file data and/or transfers, perhaps a listing or manifest file.

However, the file seems empty except for a header line (see terminal session transcript below).
Is a file with just headers normal? Or are data rows to be expected? What is the significance of the file?

The number in the rc.log file for the task is zero and all files expected to be delocalized for the task were successfully delocalized.

wm8b1-75c:call-aggregateTokensAndMakePon esalinas$ cat out.log 
Source,Destination,Start,End,Md5,UploadId,Source Size,Bytes Transferred,Result,Description
wm8b1-75c:call-aggregateTokensAndMakePon esalinas$ egrep -in '.' out.log 
1:Source,Destination,Start,End,Md5,UploadId,Source Size,Bytes Transferred,Result,Description
wm8b1-75c:call-aggregateTokensAndMakePon esalinas$ wc -l out.log 
       1 out.log
wm8b1-75c:call-aggregateTokensAndMakePon esalinas$