I happened to search the SAS.COM site using Google, and found reference to a similar-named file WORK._FMTDESC. This file happens to be generated using PROC FORMAT with the CNTLOUT= keyword. Again, this example appears similar to your post topic/reference point.
So, I would suggest reviewing your SASLOG, looking for where PROC FORMAT is creating WORK._FMTDESC, and there you will find the SAS session location responsible for creating this file.
Scott Barry
SBBWorks, Inc.