Name: Mark Feinstein E-mail Address: mfein@clark.net IDL version: IDL5.4 Platform and OS: Windows Description of Behavior: The File_Test function returns a 1 instead of a 0 if passed a null string as an argument. Example Code: IDL> Print, File_Test("") 1 Know Workarounds or Fixes: None. Test for null string before calling File_Test. RSI Technical Support Response: This has been fixed in IDL 5.5.