For file downloads, this is the name of the file to download. For file uploads, this is the name of the uploaded file.
This parameter is initialized when the FileTransfer object is created.
MobiLink first searches for the file in the userName subdirectory followed by the root directory. The root download directory
is specified via the MobiLink server's -ftr option, and the root upload directory is specified via the -ftru option.
fileName must not include any drive or path information, or the MobiLink server will be unable to find it. For example, "myfile.txt"
is valid, but "somedir\myfile.txt", "..\myfile.txt", and "c:\myfile.txt" are all invalid.