Those are probably quite normal (newlines and tabs). If the application is legitimately complaining about the newlines, perhaps it's expecting something in DOS form (where newlines are expressed by CRLF's instead of the Unix equivalent of just an LF). I'm not terribly familiar with this module, but similar problems happen when you FTP a text file from Unix to Windows (or vice-versa) without specifying an ASCII transfer method.

Does the application explain why the XML document is being rejected? An actual error message would help.