As Marilyn says, most FTP clients differentiate between two types of files: binary and ASCII. I don't think this type is included in the URL. Not only will a binary file treated as ASCII result in garbage. The file will be damaged. This is because each operating system has its own representation for an end of line sequence. I think the main reason that FTP clients worry about the "file type" is to deal with these differences and translate the "end of line sequence" from that used in the server's OS to that used in the client OS. This means that binary data will be modified if it is treated as ASCII text.
If you want/need this feature in the FTP client you are developing, then I think you will need to add your own logic to look at the data and convert EOLs as necessary. (As a disclaimer, the FTP protocol might have this built-in, but I'm unfamiliar with the specifics of the protocol to give a definite answer.)