synchonize always processes .txt files

I'm running a script that just copies one folder (plus its subfolders) to my ftp server. Here's the command line:

open ftp://xxx:yyy@zzz.com -rawsettings Utf=1
cd /home/backup
synchronize remote -mirror -delete -criteria=either -transfer=automatic "d:\Chaos Data" "Chaos Data"

Strangely, any files with a .txt extension ALWAYS get processed, even if I run the script twice in succession. It may also be that the .txt files are processed ascii whereas all the other files are binary, if that makes a difference. The txt files still have the same datestamps and sizes so should not be processed. Right?

Size of a text file changes during ascii/text mode transfer.

As you opted to use a size as criteria when selecting files for synchronization, the text files will always be considered different.

Ahh, of course, Thanks! I understand that ASCII mode changes the EOL characters (and other encoding) to handle the difference in file systems. But if I'm only doing FTP purely for backup purposes (never opening the files on the target system), wouldn't BINary be fine for all files?

Yes it would. It's even more appropriate for backup purposes.