possibly your problem is the encoding of the fo-File. If you transfer it form NT to OS390 in binary mode,
everything should be ok, but than you cannot read the file on OS390, because it is ASCII (better UTF-8) and OS390 wants to see EBCDIC.
If you transfer it as a text file, your ftp program or whatever you use should convert it to EBCDIC and you can look at it in a text editor. But than you have to manually change the encoding attribute of the file, because otherwise the XML parser assumes it is utf-8.
So try to change the fist line of the file to
<?xml version="1.0" encoding="ebcdic-cp-us"?>
(ebcdic-cp-us is an encoding that is supported by Xerces).