The FTPExtensionMap.txt file (Windows) and the FTPExtensionMapMac.txt file (Macintosh) map filename extensions to FTP transfer modes (ASCII or BINARY).
Each line in each of the two files includes a filename extension (such as GIF) and either the word ASCII or the word BINARY, to indicate which of the two FTP transfer modes should be used when transferring a file with that extension. On the Macintosh, each line also includes a creator code (such as DmWr) and a file type (such as TEXT). When you download a file with the given filename extension on the Macintosh, Dreamweaver assigns the specified creator and file type to the file.
If a file that you are transferring doesn’t have a filename extension, Dreamweaver uses the BINARY transfer mode.
Note:
Dreamweaver cannot transfer files in Macbinary mode. If you need to transfer files in Macbinary mode, you must use another FTP client.
The following example shows a line (from the Macintosh file) that indicates that files with the extension .html should be transferred in ASCII mode:
HTML DmWr TEXT ASCII