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This article contains a brief description of the MacBinary file format. A detailed description and technical information is available from Apple's Developer Web Site.
DISCUSSION Overview Because of the way the Macintosh file system keeps track of files, there was a need to provide this tracking information when transmitting files through a modem. A committee was established, which developed the original MacBinary and later the MacBinary II and MacBinary III format. These formats remain functionally identical, though the MacBinary II format added additional information to maintain the integrity of the file system information and the MacBinary III format added support for extended Finder information introduced in Mac OS 8. Macintosh Files Every Macintosh file (through Mac OS 9) contains two parts: a resource fork, which contains data used by an application, such as menus, fonts, and icons; and a data fork, which contains data specific to an application. Additionally, information about the file such as the file type, creator code, Get Info comments, creation date, and modification date are stored by the file system. Originally, telecommunication programs only sent one part of a Macintosh file (the data fork). This meant that when a binary file was transferred from a Macintosh it lost its icon, and Type & Creator information. Since this information is important to the Macintosh file system, MacBinary was developed. MacBinary MacBinary is not a transfer protocol like Xmodem, Kermit, or Zmodem. Instead, it is used in conjunction with a transfer protocol, although it is independent of that protocol. MacBinary can be used when binary files are placed on an FTP server or emailed through the Internet. It allows the various parts of a Macintosh file to be combined into a single chunk of data which can be sent anywhere and downloaded to any kind of computer, and then be reconstructed into the original Macintosh file at the end of its journey. MacBinary consists of 128 bytes, which are added to beginning of the file. Most Macintosh telecommunication and Internet programs automatically use MacBinary when a binary file is sent. Most applications also allow you to turn off MacBinary. If you are sending a binary file such as a TIFF or JPEG file to someone who uses a Windows computer, you must turn off MacBinary. If you do not turn off MacBinary, the additional 128 bytes at the beginning of the file will corrupt the file. There are ways of removing the MacBinary information, but most of these are designed for Macintosh. At one time there were a couple of MS-DOS terminal programs that automatically detected MacBinary files and stripped off the first 128 bytes of the file. MacBinary versus BinHex and UUencode MacBinary, unlike BinHex or UUencode, does not convert the data into a text representation of the binary data. The following articles provide additional information on UUencode and BinHex: Online Archive Article 18499: " What Is Binhex & Where To Obtain It " Article 18758: " UUencode & UUdecode: Explained " These articles can help you decide the best way to send your files through email systems. If you are placing binary files such as applications, compressed binary files (StuffIt, Compactor), or other Macintosh specific binary files on a remote file server or FTP site here is a chart that can help you determine if you need to use MacBinary or not.
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