Joined: 30 Nov 2013 Posts: 485 Location: The Universe
Was the transfer agent really IBM FTP or some other transfer agent? My old version of a 3270 emulator did that trick with its file transfer agent, though it was corrected by a newer version of the emulator.
It is an EOF marker - but do not ask me why some files have it and some do not - I've just checked a whole lot of my text files before finding one showing that character. It doesn't hurt to delete it - I think it just gets added back.
If you are really concerned then go to a PC forum somewhere or Google 'eof marker in text documents'